Reimagining Nuclear Arms Control: A Comprehensive Approach

The governments of China, Russia, and the United States all express support for arms control.¹ However, they disagree profoundly about its purposes and preconditions. At the root of this disagreement are important and growing differences between the threats that concern the United States and those that concern China and Russia. Having largely failed to bridge this divide, these states are now responding to their perceived threat environments in ways that drive nuclear arms racing and thus exacerbate interstate tensions. Should these tensions spill over into war, their responses could spark inadvertent escalation and nuclear use. Arms control could help to manage these risks and enhance the security of all three states—if they can find a mutually acceptable way forward.

The New Nuclear Arms Race

To date, the renewed U.S.-Russian nuclear arms race has been largely qualitative but could soon turn quantitative. One driver is an imbalance in conventional forces. Many of Russia’s neighbors, including Eastern European members of the North Atlantic Treaty Organization (NATO), are concerned about being coerced by Moscow through either nonmilitary or military means. Moreover, because of Russia’s conventional superiority around the Baltic region, Estonia, Latvia, and Lithuania also worry about a full-scale invasion. These concerns have led the United States to keep about 100 nonstrategic nuclear weapons (NSNWs)—out of a total of about 230 such weapons—deployed in Europe.² (In unhelpful language inherited from the Cold War, Russia and the United States generally use the term “strategic” to describe nuclear weapons with sufficient range to reach the other’s homeland from deployment locations in the possessor’s homeland or, in the case of sea-based weapons, from firing locations away from the other’s coast.³)

Russia, meanwhile, views itself as conventionally inferior to NATO across Europe as a whole. It relies heavily on nuclear weapons—especially NSNWs—for deterring large-scale aggression. The U.S. Department of Defense assesses that Russia has “up to 2,000” nonstrategic warheads and may be increasing that number.⁴ Moreover, Moscow is developing and deploying various new types of NSNWs, including, most controversially, the SSC-8—a dual-use ground-launched cruise missile that the United States assesses, almost certainly correctly, was developed in violation of the Intermediate-Range Nuclear Forces (INF) Treaty. (Dual-use weapons can accommodate a nuclear or nonnuclear warhead.)

Russia believes that the United States is seeking capabilities— particularly nonnuclear ones—to undermine its nuclear deterrent.

Washington believes that these developments reflect a growing Russian willingness to threaten to use, or even to use, nuclear weapons early in a conflict—particularly following an invasion of the Baltic states—in the hope of compelling the United States to stand down.⁵ Russian officials have strenuously denied that their nuclear doctrine embraces this concept, which is often called “escalate to de-escalate” in Western discourse.⁶ These denials have not assured Washington. Indeed, to correct the “mistaken Russian perception” that Moscow’s advantage in NSNWs would provide it with “a coercive advantage,” the United States has deployed low-yield warheads on some Trident D5 sea-launched ballistic missiles (SLBMs) and has started to acquire a nuclear-armed sea-launched cruise missile (SLCM), though the administration of U.S. President Joe Biden may cancel this program.⁷ Meanwhile, the United States’ withdrawal from the INF Treaty, ostensibly because of Russia’s deployment of the SSC-8 cruise missile, has opened the door to a competition in medium- and intermediate-range ground-launched missiles (though only Russian weapons are likely to be nuclear-capable).

The U.S.-Russian competition is also playing out with strategic weapons. Russia believes that the United States is seeking capabilities—particularly nonnuclear ones—to undermine its nuclear deterrent. Moscow fears that, after the further development and deployment of both offensive and defensive systems, the United States could be in a position to launch nuclear or nonnuclear preemptive strikes on Russia’s nuclear forces and then use ballistic missile defenses to mop up any surviving Russian weapons fired in retaliation. Stripped of its nuclear deterrent in this way, Moscow believes it would be left vulnerable to U.S. coercion.

Russia’s defense spending suggests that these concerns are acute. In 2018, for example, Russian President Vladimir Putin announced the development of three new kinds of “exotic” strategic nuclear delivery systems as a way of preserving Russia’s ability to defeat U.S. defenses.⁸ Russia has since deployed one of these systems—an intercontinental hypersonic glider, Avangard. The other two—a nuclear-powered cruise missile, Burevestnik, and a nuclear-powered torpedo, Poseidon—remain under development.

The New Strategic Arms Reduction Treaty (New START) helps to manage this competition by limiting all currently deployed U.S. and Russian strategic weapons, including Avangard. Following its extension in early 2021, this treaty will remain in force until 2026. However, the prospects for negotiating a follow-on agreement are unclear. Without a strategic arms limitation agreement in place, the result could be a renewed numerical arms race in strategic weapons.

China is not a party to New START or any other agreement that limits its nuclear forces. Currently, those forces are significantly smaller than either Russia’s or the United States’. The United States estimates that China’s nuclear warheads number in the “the low-200s.”⁹ By comparison, the United States has indicated that, as of September 2020, it possessed 3,750 nuclear warheads, while Russia has likely well in excess of 4,000.¹⁰ However, China is steadily expanding its nuclear arsenal without giving any indication of its intended endpoint. The U.S. Department of Defense expects China to “at least double” its warhead stockpile over the next decade.¹¹

Like Moscow, Beijing believes that the United States seeks to undermine its nuclear deterrent.¹² The commander of U.S. Northern Command, which is responsible for homeland defense, has publicly assessed that China is “investing heavily to improve the survivability and penetrability of its nuclear forces in an effort to guarantee its ability to retaliate following a strategic first strike.”¹³ To meet these objectives, Beijing is improving and expanding its long-range nuclear forces. Many of its programs are focused on ensuring that its nuclear forces will continue to have the ability to penetrate U.S. missile defenses for the indefinite future. Official U.S. sources, for example, have indicated that China has deployed intercontinental ballistic missiles (ICBMs) armed with multiple warheads and is “looking at” nuclear-powered cruise missiles and torpedoes.¹⁴ According to media reports, U.S. officials also believe that, in the summer of 2021, China conducted two tests of a novel nuclear-weapon delivery system that first enters orbit before releasing a hypersonic glider.¹⁵ To complicate any U.S. attempt to attack its nuclear forces preemptively, China is upgrading its mobile ground-based ICBM launchers, deploying six nuclear-powered ballistic missile submarines (SSBNs), and constructing at least 230 missile silos (and possibly many more), though it may not be intending to place an ICBM in every silo, at least initially.¹⁶ (Launchers are any device used to store and launch missiles. They include truck- and rail-based systems, silos, fixed above-ground systems, and launch tubes on submarines.)

Separately, China is also modernizing and expanding its force of regional missiles, including dual-use weapons.¹⁷ This development is probably motivated by the desire to acquire more credible options for limited nuclear use rather than concerns about force survivability.

Growing Escalation Dangers

In a deep crisis or a conventional conflict between the United States and China or Russia, the concerns about force vulnerability that drive arms racing could spark inadvertent escalation. Crisis instability is one potential danger.¹⁸ If the United States’ adversary concluded that a U.S. attack on its nuclear forces was imminent, it might issue nuclear threats or engage in limited nuclear use to try to terrify Washington into backing off. If the adversary were Russia, then in extreme circumstances, it might even attack U.S. nuclear forces preemptively to try to protect itself (China’s nuclear forces are currently too small to even attempt such an operation).

This risk of crisis instability is being exacerbated by the growing entanglement between the nuclear and nonnuclear domains.¹⁹ For much of the Cold War, threats to nuclear weapons came largely from other nuclear weapons. Today, both China and Russia perceive a real and growing danger of preemptive nonnuclear attacks on their nuclear forces—including with cyber capabilities, cruise missiles, and, in the future, hypersonic boost-glide missiles—and of interception after the launch of those forces by nonnuclear missile defense interceptors.

The United States, by contrast, is much less concerned about the survivability of its nuclear forces. Entanglement, however, is also undermining the survivability of nuclear command, control, communication, and intelligence (C3I) capabilities—including the United States’—and creating new escalation risks. For early-warning and long-range communications especially, the U.S. nuclear C3I system relies on a relatively small number of impossible-to-hide assets in space and on the ground. They are becoming increasingly vulnerable to the improving anti-satellite and long-range conventional strike capabilities being acquired by China and Russia. The U.S. nuclear C3I system is almost certainly vulnerable to cyber attacks too (though it is more difficult to assess whether the risk of successful attacks is increasing or decreasing).²⁰

To compound these vulnerabilities, many C3I assets—including ground-based radars and communication transmitters and early-warning and communication satellites—support both nuclear and nonnuclear operations. In a conventional conflict, an adversary might attack these assets to undermine the effectiveness of U.S. nonnuclear operations. However, such attacks could have the effect of degrading U.S. nuclear C3I systems. As a result, Washington might interpret them as the prelude to nuclear use and escalate the conflict in an attempt to coerce the adversary into backing down. In fact, the United States has explicitly threatened to resort to nuclear use should its nuclear C3I capabilities come under nonnuclear attack.²¹ (China and Russia are almost certainly concerned about the survivability of their nuclear C3I systems too. However, the extent to which China’s system, in particular, depends on dual-use assets is less clear.)

Unilateral efforts to enhance the resilience and survivability of states’ nuclear forces and their C3I systems can enhance security but typically involve trade-offs between different escalation risks. For example, China is currently developing a strategic early-warning system that could enable it to launch its nuclear forces before they were destroyed in an incoming attack.²² While a launch-under-attack capability could increase Beijing’s confidence in the survivability of its nuclear forces, it could also lead to China’s mischaracterizing, say, a U.S. missile test in the Pacific region as an attack—potentially catalyzing a nuclear response.

An Agenda for Cooperative Risk Reduction: Nine Practical Measures

Arms control offers a complementary, proven, and potentially powerful approach to managing the risks of both arms racing and inadvertent escalation and, more generally, to reducing the risk of conflict. The term “arms control” is used here in its broad, original sense to mean “all the forms of military cooperation between potential adversaries” intended to improve mutual security.²³ Such cooperation includes treaty-mandated limits on nuclear forces with intrusive verification and extends to confidence building, transparency, and behavioral norms.

A first step in reviving arms control is for Russia and the United States to commence negotiations toward a follow-on treaty to New START. Two authors of this report recently set out a detailed concept for such an agreement.²⁴ To avoid overloading negotiations and thus risking their collapse, the scope of a New START follow-on should be limited to strategic offensive arms, including new kinds of such weapons (nuclear and nonnuclear) developed since New START’s entry into force. Such an agreement would help mitigate the acute dangers created by Russia’s and the United States’ possessing large and uniquely destructive forces of strategic nuclear weapons that threaten one another.

A bilateral treaty on strategic offensive arms could not manage all the risks outlined above, however. Its focus on strategic arms would preclude any limitation of Russia’s and the United States’ NSNWs. And as a bilateral agreement, it would not regulate any Chinese capabilities and would also, therefore, be the wrong forum to manage the danger of misidentifying a missile test as an attack. Further, because its scope would be restricted to offensive arms, it would do nothing to address Chinese and Russian concerns about ballistic missile defense and not enough to manage threats to nuclear C3I capabilities.

In the near term, politically binding transparency and confidence-building measures present the most promising means to start addressing these lacunae, not least because of the difficulties posed by treaty ratification procedures within the United States. Such measures should be negotiated alongside a New START follow-on and would both complement and enable it. This report proposes six such measures:

• A U.S.-Russian data exchange for SLCMs and nonnuclear sea-launched boost-glide missiles (SLBGMs)
• A U.S.-Russian transparency regime for empty actual or suspected warhead storage facilities
• A U.S.-Russian confidence-building regime for European Aegis Ashore ballistic missile defense installations
• A U.S.-Chinese fissile material cutoff and transparency regime
• A trilateral launch notification agreement for ballistic missiles, missile defense tests, and space launches
• A trilateral agreement to establish keep-out zones around high-altitude satellites

Over the longer term, bilateral and trilateral treaties could be negotiated to provide a more durable and robust risk-reduction architecture. Three such agreements, with varying levels of ambition, are proposed here:

• A trilateral treaty to prohibit the development and deployment of space-based missile defenses
• A trilateral treaty to limit ground-based missile launchers, SLBM launchers, and bombers
• A U.S.-Russian limit on all nuclear warheads

Although these proposals vary significantly in their level of ambition, none likely present any currently insurmountable technical barriers—except the treaty to limit all warheads for which significant additional intragovernmental preparatory work would be required. Moreover, implementing any of them would help reduce nuclear dangers. Therefore, in laying out these proposals, we generally urge Beijing, Moscow, and Washington to adopt them. While calling for progress, however, we recognize that politics create real roadblocks, especially to the more ambitious proposals. The pace of progress on arms control will be constrained by the overall state of the U.S.-Russian and U.S.-Chinese relationships, and, to a lesser extent, the Russian-Chinese relationship. 

Cross-Cutting Implementation Issues

The proposals detailed here are intended to be practically useful for the officials who would be charged with negotiating them. While each proposal raises some unique difficulties, a few implementation challenges would be common to many of them. Determining a missile’s range, largely a technical issue, could be difficult (see appendix A). Exchanging data and facilitating inspections on the territory of U.S. allies—technically more straightforward—could be politically contentious.

Most arms control regimes require a dedicated mechanism to exchange data. Normal diplomatic channels may occasionally suffice, but they are ill-suited to rapid exchanges, especially involving large quantities of information. For this reason, Russia and the United States agreed, in 1987, to each set up a Nuclear Risk Reduction Center to enable reliable and rapid communications, including arms control notifications (the United States has since renamed its center the National and Nuclear Risk Reduction Center). These centers provide Russia and the United States with an already established, dedicated communication channel that would be useful in implementing virtually all the proposals described in this report.

But the proposals including China would also require data exchanges, and it is unclear whether Beijing has a similar center or organization. It may have one to facilitate its current participation in other arms control regimes. Perhaps the most relevant such regime is a 2009 Russian-Chinese launch notification agreement (discussed further in chapter 5) that requires the parties to maintain a communication channel. However, there is no publicly available information on what Chinese entity is responsible for sending and receiving notifications, thus making it difficult to assess this channel’s utility for other applications. Regardless, even if Beijing and Moscow have a dedicated communication channel suitable for exchanging arms control notifications, Beijing and Washington do not.

By agreeing to establish a communication channel, Beijing would be tacitly acknowledging the potential value of arms control and, in particular, of transparency—a step that it has not yet taken.

A U.S.-Chinese link and, if needed, an additional Russian-Chinese link would be useful in facilitating further cooperation both bilaterally and trilaterally. Although establishing the former channel would be straightforward from a technical perspective, the process would be plagued by politics. By agreeing to establish it, Beijing would be tacitly acknowledging the potential value of arms control and, in particular, of transparency—a step that, as discussed below, it has not yet taken.

Regarding inspections, a number of proposals would require them of specified kinds of U.S. military equipment located on the territory of its allies (and of any similar Chinese or Russian equipment deployed outside of their national territory in the future). While such inspections could be politically sensitive, the INF Treaty provides a clear precedent. Although it was negotiated bilaterally, this agreement permitted the Soviet Union and then Russia to conduct inspections at various bases in five NATO states. These inspections were facilitated through a separate agreement between the United States and those NATO states.²⁵ A similar approach, which would require close coordination between the United States and its allies, should be adopted here.²⁶

The Politics of Arms Control

U.S. priorities for arms control largely relate to China’s and Russia’s nuclear forces.²⁷ The Biden administration seeks to preserve the existing limits on Russia’s strategic forces and extend them to capture Moscow’s developmental exotic strategic nuclear weapons and its nonstrategic nuclear forces. Where China is concerned, the administration has identified risk reduction as its most immediate priority, while also seeking to prevent “unnecessary arms races”—which, in practice, means limiting the growth of China’s nuclear forces.²⁸ By contrast, China and Russia are primarily worried about developments in U.S. nonnuclear technology—precision strike capabilities and missile defenses, in particular—which those states fear could undermine the survivability of their nuclear forces.

As a result of this divergence, it is becoming ever more difficult to craft individual arms control proposals that simultaneously further all three states’ interests—at least as they define them—even if the obligations enshrined in each proposal are entirely reciprocal. Indeed, many of the proposals outlined in this report are intended to address the concerns of just one or two states.

It is becoming ever more difficult to craft individual arms control proposals that simultaneously further all three states’ interests— at least as they define them—even if the obligations enshrined in each proposal are entirely reciprocal.

One practical way to overcome this problem would be to negotiate over multiple proposals simultaneously. Even if no single measure were acceptable to all the parties concerned, a package deal, comprising two or more measures, could nonetheless be mutually beneficial. For example, Russia and the United States could agree to simultaneously implement one confidence-building measure focused on ballistic missile defense and another covering NSNWs. While such packages are suggested here, it is difficult to predict exactly which agreements may be within reach at any given time; therefore, success would depend on skillful diplomacy to take advantages of opportunities as they arise.

More generally, because of the potentially cataclysmic consequences of a nuclear war—which, because of radioactive fallout, climatic effects, and economic collapse, would be experienced by every state, including nonbelligerents—China, Russia, and the United States have a clear joint interest in avoiding inadvertent nuclear escalation, thereby creating much stronger shared interests than they often realize. Measures that reduced the likelihood of such escalation would create benefits for every participant, even if they did not address the concerns of every participant. In theory, this realization should leave Beijing, Moscow, and Washington more willing to address one another’s concerns—though, as a practical matter, they are likely to find the logic of negotiating package deals more compelling.

Another consideration for all three states—but particularly Russia and the United States—is their commitment, under Article VI of the Nuclear Non-Proliferation Treaty, “to pursue negotiations in good faith on effective measures relating to cessation of the nuclear arms race at an early date and to nuclear disarmament.” The proposals in this report would advance the goals of Article VI in various ways. Limits on fissile material production, warheads, and missiles are necessary steps toward a world without nuclear weapons, while inspections of storage facilities to verify the absence of nuclear warheads would be needed as part of any credible regime to verify the transition to such a world. In the meantime, many of these same proposals would help to curtail arms racing—as would enhanced transparency around ballistic missile defenses and sea-based missiles. Member states have also agreed that the purpose of Article VI can be advanced through “policies that could . . . lessen the danger of nuclear war.”²⁹ A number of proposals—including launch notifications and keep-out zones for high-altitude satellites—fall into this category. At a time when many non-nuclear-weapon states are deeply skeptical of the nuclear-weapon states’ willingness to live up to their disarmament commitments—and when there is little prospect of any major breakthrough in efforts to achieve a world without nuclear weapons—the proposals set out here offer a way to make visible progress on Article VI and thus bolster the nonproliferation regime.

Beyond the problem of finding enough shared interest to catalyze progress, China, Russia, and the United States also have their own specific concerns about arms control, even while they say they support it in principle. China is the most skeptical. It is not a party to any nuclear arms control agreement other than the 1968 Nuclear Non-Proliferation Treaty (though, like the United States, it has signed but not ratified the 1996 Comprehensive Nuclear-Test-Ban Treaty). Recently, Beijing has been very clear about its lack of interest in negotiations over nuclear limitations—at least until the United States makes deep reductions in its nuclear forces.³⁰ Beijing has failed, however, to indicate whether it believes that China’s security could be enhanced by other forms of arms control—though Chinese scholars have expressed a general concern that greater transparency would risk undermining the survivability of its nuclear forces.

China has previously participated in nonnuclear arms control with potentially hostile foreign powers when there have been clear benefits to doing so.

Yet the benefits and risks of transparency, as an abstract principle, are not at issue; the effects of specific proposals on Chinese security are. Indeed, China has previously participated in nonnuclear arms control with potentially hostile foreign powers when there have been clear benefits to doing so. For example, in the late 1990s, when Chinese-Russian relations were significantly worse than they are today, China negotiated a verified treaty that limits conventional weapons near its borders with Russia and three Central Asian republics.³¹ In that spirit, Chinese officials and analysts should consider what arms control measures related to nuclear weapons, missiles, and missile defenses would advance Chinese interests. They should then explore the trade-space with their U.S. counterparts—first in unofficial and then official dialogues—with the goal of developing mutually beneficial packages.³²

Russia and the United States, meanwhile, each have various concerns about engaging the other. In recent years, the United States has raised frequent and legitimate complaints about Russian compliance with various existing agreements and is therefore understandably hesitant to enter into new ones.³³ At the same time, Moscow points to the United States’ withdrawal from a number of arms control and nonproliferation agreements over the past two decades as a reason for skepticism about engaging Washington.³⁴ (Two of these withdrawals, from the 1972 Anti-Ballistic Missile Treaty and the 2015 Joint Comprehensive Plan of Action, were particularly damaging to U.S. credibility as Washington assessed that the Soviet Union and Iran, respectively, were complying with their commitments at the time it left the agreements.) Legally, abrogating obligations is certainly preferable to violating them; politically, however, Russian concerns about entering into new agreements with the United States also are understandable (and shared by other countries too). None of these concerns can be addressed through the text of an agreement, yet they have not precluded cooperation where it has been clearly mutually beneficial—as most recently illustrated by the extension of New START.

One question that Moscow and Washington will have to address is whether agreements should be politically or legally binding. The United States is generally supportive of the principle of politically binding transparency and confidence-building measures—not least because they obviate the challenge of obtaining the Senate’s advice and consent for treaty ratification—even if, in practice, Washington has sometimes shown a lack of willingness to elaborate or explore specific proposals. Russia, by contrast, often expresses skepticism about politically binding agreements, dismissing them as “verification for the sake of verification, transparency for the sake of transparency.”³⁵ It seeks the greater predictability that is supposed to come with legally binding agreements. Moreover, Russian officials privately argue that it is more politically difficult and time consuming for the United States to withdraw from treaties.³⁶

In June 2021, Russian Deputy Foreign Minister Sergey Ryabkov indicated a clear interest in negotiating legally and politically binding instruments alongside one another.

In practice, however, the benefits of treaties have not proven to be so marked. Given the fate of the Anti-Ballistic Missile Treaty, the INF Treaty, and the 1992 Open Skies Treaty, it is far from clear that a U.S. administration actually pays a greater political price for withdrawing from a treaty than from a politically binding agreement such as the Joint Comprehensive Plan of Action. And, although treaties contain withdrawal timelines, the minimum notification periods are often quite short—typically just six months.

Moreover, Russia has sometimes shown flexibility and, despite its concerns, has accepted politically binding agreements. For example, in 1988, the Soviet Union and the United States conducted the Joint Verification Experiment, in which each state measured the yield of a nuclear test conducted by the other, pursuant to a politically binding agreement. More recently, in June 2021, Russian Deputy Foreign Minister Sergey Ryabkov indicated a clear interest in negotiating legally and politically binding instruments alongside one another, stating that Russia and the United States could “decide to adopt a package of interrelated arrangements and/or agreements that might have different status if necessary.”³⁷

The hybrid approach advocated here—which starts with a treaty that constrains strategic offensive arms and is implemented alongside transparency and confidence-building measures—is consistent with Ryabkov’s suggestion and offers the most practical and plausible way forward. Politically binding measures currently represent the only viable way to address issues that, for technical or political reasons, cannot be managed through treaties. Moreover, historically, politically binding agreements have facilitated the development of legally binding ones. For example, the Joint Verification Experiment facilitated the 1974 Threshold Test Ban Treaty’s entry into force in 1990. In this spirit, the development of politically binding confidence-building measures should be the start of a process, not the end of one.

Notes

¹ Fu Cong, Statement at the General Debate of the First Committee, 74th Session of the United Nations General Assembly, New York, October 12, 2019, available at https://web.archive.org/web/20211023032402/https://www.fmprc.gov.cn/mfa_eng/wjb_663304/zzjg_663340/jks_665232/tyylb_665254/t1707314.shtml; Ministry of Foreign Affairs of the Russian Federation, “Russia’s Position at the Seventy-Fifth Session of the UN General Assembly,” July 23, 2020, https://www.mid.ru/en/web/guest/foreign_policy/international_safety/conflicts/-/asset_publisher/xIEMTQ3OvzcA/content/id/4252717; and Joseph R. Biden, Jr., “Interim National Security Strategic Guidance,” March 2021, 13, https://www.whitehouse.gov/wp-content/uploads/2021/03/NSC-1v2.pdf.

² Hans M. Kristensen and Matt Korda, “United States Nuclear Weapons, 2021,” Bulletin of the Atomic Scientists 77, no. 1 (2021): 44.

³ SLCMs are an exception (hence the qualifier “generally”) because, for practical reasons, they have never been accountable under “strategic” arms control treaties.

⁴ U.S. Department of Defense, “Nuclear Posture Review,” February 21, 2018, 9, 53, https://media.defense.gov/2018/Feb/02/2001872886/-1/-1/1/2018-NUCLEAR-POSTURE-REVIEW-FINAL-REPORT.PDF.

⁵ Ibid, 53–54.

⁶ “U.S. Claims on Russia’s ‘Escalation for De-escalation’ Doctrine Are Wrong—Envoy,” TASS, April 8, 2019, https://tass.com/politics/1052755.

⁷ U.S. Department of Defense, “Nuclear Posture Review,” 53.

⁸ Vladimir Putin, “Presidential Address to the Federal Assembly,” Moscow, March 1, 2018, http://en.kremlin.ru/events/president/news/56957. Putin also announced Kinzhal, an air-launched ballistic missile. So far, this system has been deployed only on MiG-31 aircraft and lacks the range to reach the United States. On managing the possibility that this weapon could be deployed on aircraft with longer ranges, see Pranay Vaddi and James M. Acton, “A ReSTART for U.S.-Russian Nuclear Arms Control: Enhancing Security Through Cooperation,” Carnegie Endowment for International Peace, October 2, 2020, 12–13, https://carnegieendowment.org/files/Acton_Vaddi_ReStart.pdf.

⁹ Office of the Secretary of Defense, “Military and Security Developments Involving the People’s Republic of China,” Annual Report to Congress, 2020, 85, https://media.defense.gov/2020/Sep/01/2002488689/-1/-1/1/2020-DOD-CHINA-MILITARY-POWER-REPORT-FINAL.PDF.

¹⁰ These figures exclude warheads awaiting dismantlement. U.S. Department of State, Bureau of Arms Control, Verification and Compliance, “Transparency in the U.S. Nuclear Weapons Stockpile,” fact sheet, October 5, 2021, https://www.state.gov/transparency-in-the-u-s-nuclear-weapons-stockpile/; and Hans M. Kristensen and Matt Korda, “Russian Nuclear Weapons, 2021,” Bulletin of the Atomic Scientists 77, no. 2 (2021): 91.

¹¹ Office of the Secretary of Defense, “Military and Security Developments Involving the People’s Republic of China,” 85.

¹² For a particularly nuanced and insightful analysis, see Tong Zhao, “Narrowing the U.S.-China Gap on Missile Defense: How to Help Forestall a Nuclear Arms Race,” Carnegie Endowment for International Peace, June 29, 2020, 11–29, https://carnegieendowment.org/files/Zhao_USChina_MissileDefense.pdf.

¹³ Terrence J. O’Shaughnessy, testimony before the U.S. Senate Armed Services Committee, February 13, 2020, 6, https://www.armed-services.senate.gov/imo/media/doc/OShaughnessy_02-13-20.pdf.

¹⁴ Office of the Secretary of Defense, “Military and Security Developments Involving the People’s Republic of China,” 56; and Jamey Keaten, “U.S. Envoy Warns China ‘Looking at’ New Nuclear Technologies,” July 8, 2021, https://apnews.com/article/europe-china-technology-government-and-politics-39029491f5863f10809dbbfc40862693.

¹⁵ Demetri Sevastopulo, “China Conducted Two Hypersonic Weapons Tests This Summer,” Financial Times, October 21, 2021, https://www.ft.com/content/ba0a3cde-719b-4040-93cb-a486e1f843fb. See also O’Shaughnessy, testimony before the U.S. Senate Armed Services Committee. It is unclear whether the glider mentioned by O’Shaughnessy is the same one described in the Financial Times report.

¹⁶ Office of the Secretary of Defense, “Military and Security Developments Involving the People’s Republic of China,” 45, 56; Joby Warrick, “China Is Building More Than 100 New Missile Silos in Its Western Desert, Analysts Say,” Washington Post, June 30, 2021, https://www.washingtonpost.com/national-security/china-nuclear-missile-silos/2021/06/30/0fa8debc-d9c2-11eb-bb9e-70fda8c37057_story.html; William J. Broad and David E. Sanger, “A 2nd New Nuclear Missile Base for China, and Many Questions About Strategy,” New York Times, July 26, 2021, https://www.nytimes.com/2021/07/26/us/politics/china-nuclear-weapons.html; and James M Acton, “Don’t Panic About China’s New Nuclear Capabilities,” Washington Post, July 27, 2021, https://www.washingtonpost.com/politics/2021/06/30/dont-panic-about-chinas-new-nuclear-capabilities/. A third Chinese silo field may also be under construction, see Rod Lee, “PLA Likely Begins Construction of an Intercontinental Ballistic Missile Silo Site Near Hanggin Banner,” Air University, August 12, 2021, https://www.airuniversity.af.edu/CASI/Display/Article/2729781/pla-likely-begins-construction-of-an-intercontinental-ballistic-missile-silo-si/.

¹⁷ Office of the Secretary of Defense, “Military and Security Developments Involving the People’s Republic of China,” 55–56.

¹⁸ See, for example, Caitlin Talmadge, “Would China Go Nuclear? Assessing the Risk of Chinese Nuclear Escalation in a Conventional War With the United States,” International Security 41, no. 4 (2017): 50–92.

¹⁹ James M. Acton, “Escalation Through Entanglement: How the Vulnerability of Command-and-Control Systems Raises the Risks of an Inadvertent Nuclear War,” International Security 43, no. 1 (2018): 56–99; and James M. Acton, ed., “Entanglement: Russian and Chinese Perspectives on Non-Nuclear Weapons and Nuclear Risks,” Carnegie Endowment for International Peace, November 8, 2017, https://carnegieendowment.org/files/Entanglement_interior_FNL.pdf.

²⁰ U.S. Department of Defense, Defense Science Board, “Task Force Report: Resilient Military Systems and the Advanced Cyber Threat,” Office of the Under Secretary of Defense for Acquisition, Technology and Logistics, January 2013, 6, https://nsarchive2.gwu.edu/NSAEBB/NSAEBB424/docs/Cyber-081.pdf.

²¹ U.S. Department of Defense, “Nuclear Posture Review,” 21.

²² Office of the Secretary of Defense, “Military and Security Developments Involving the People’s Republic of China,” 88–89.

²³ Thomas C. Schelling and Morton H. Halperin, Strategy and Arms Control (New York: Twentieth Century Fund, 1961), 2.

²⁴ Vaddi and Acton, “A ReSTART for U.S.-Russian Nuclear Arms Control.”

²⁵ The text of this agreement is available from the Office of the Assistant Secretary of Defense for Acquisition, “INF Treaty: Basing Countries Agreement,” https://www.acq.osd.mil/asda/ssipm/sdc/tc/inf/INF-Basing.html. Following the dissolution of the Soviet Union, the United States conducted inspections in Belarus, Kazakhstan, Russia, and Ukraine. Washington negotiated such inspection rights as necessary directly with the relevant governments. U.S. Department of State, Bureau of Arms Control, Verification and Compliance, “Treaty Between the United States of America and the Union of Soviet Socialist Republics on the Elimination of Their Intermediate-Range and Shorter-Range Missiles (INF Treaty),” https://2009-2017.state.gov/t/avc/trty/102360.htm.

²⁶ The 1990 Conventional Forces in Europe Treaty (to which individual NATO and Warsaw Pact members were signatories) provides a different model. However, this treaty limited equipment belonging to all parties—not just the United States and the Soviet Union—making it less relevant than the INF Treaty to the proposals in this report.

²⁷ Bonnie Jenkins, “Nuclear Arms Control: A New Era?,” Seventeenth Annual NATO Conference on WMD Arms Control, Disarmament, and Nonproliferation, Copenhagen, Denmark, September 6, 2021, https://www.state.gov/under-secretary-bonnie-jenkins-remarks-nuclear-arms-control-a-new-era/.

²⁸ Ibid.

²⁹ 2010 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons, “Final Document,” NPT/CONF.2010/50 (Vol. I), New York, 2010, 21, https://www.nonproliferation.org/wp-content/uploads/2015/04/2010_fd_part_i.pdf.

³⁰ Ministry of Foreign Affairs of the People’s Republic of China, “Department of Arms Control and Disarmament Holds Briefing for International Arms Control and Disarmament Issues,” Beijing, July 8, 2020, available at https://web.archive.org/web/20211014015131/https://www.fmprc.gov.cn/mfa_eng/wjbxw/t1795979.shtml.

³¹ The 1997 Agreement on the Mutual Reduction of Military Forces in the Border Area.

³² For a detailed discussion of arms control proposals that would advance mutual security, see Tong Zhao, “Practical Ways to Promote U.S.-China Arms Control Cooperation,” Carnegie Endowment for International Peace, October 7, 2020, https://carnegietsinghua.org/2020/10/07/practical-ways-to-promote-u.s.-china-arms-control-cooperation-pub-82818.

³³ Examples abound in U.S. Department of State, “Adherence to and Compliance With Arms Control, Nonproliferation, and Disarmament Agreements and Commitments,” April 2021, https://www.state.gov/wp-content/uploads/2021/04/2021-Adherence-to-and-Compliance-With-Arms-Control-Nonproliferation-and-Disarmament-Agreements-and-Commitments.pdf.

³⁴ Ministry of Foreign Affairs of the Russian Federation, “Deputy Foreign Minister Sergey Ryabkov’s Interview With Kommersant,” December 19, 2018, https://www.mid.ru/en/foreign_policy/news/-/asset_publisher/cKNonkJE02Bw/content/id/3449525.

³⁵ “The USA Continues Previous Course, Which May Be Formulated Very Briefly: Russia Is a Geostrategic Enemy,” International Affairs, October 16, 2019, https://interaffairs.ru/news/show/24166 (in Russian).

³⁶ Personal communication, senior Russian official, July 2021.

³⁷ Italics added for emphasis. Sergey Ryabkov, “Keynote Address,” 2021 Carnegie International Nuclear Policy Conference, June 22, 2021, 5, https://ceipfiles.s3.amazonaws.com/pdf/Sergey+Ryabkov+Keynote_Transcript.pdf.

Modern SLCMs are highly capable. They are accurate, difficult to detect and track, and have sufficient ranges—approaching 3,000 kilometers (1,900 miles)—to reach targets deep within an adversary’s interior.¹ Both Russia and the United States deploy large forces of conventional SLCMs, creating escalation risks. Russia is concerned that U.S. weapons threaten its nuclear forces, particularly mobile ICBMs but also docked SSBNs, heavy bombers on the ground, and perhaps even silo-based ICBMs.² Meanwhile, Russian nonnuclear SLCMs threaten critical U.S. military assets, including ground-based C3I capabilities that support nuclear operations, and potentially national and military leadership.

The development of SLCMs can also feed arms racing. The United States is acquiring (for now, at least) a nuclear-armed SLCM in response to its concerns about Russian NSNWs, which include SLCMs. If deployed, this new U.S. missile will likely further exacerbate Moscow’s concerns about the survivability of its nuclear forces, potentially catalyzing a Russian response.

SLBGMs have not yet been deployed by either state. But if various technical challenges are overcome, these missiles could be as accurate as SLCMs, while traveling much faster and over potentially greater distances.³ As such, they could exacerbate both escalation risks and arms racing. The United States is currently developing nonnuclear SLBGMs.⁴ There is no public evidence of an equivalent Russian effort—though it would come as no surprise to learn that Moscow has initiated one. Russian SLBGMs would most likely be nuclear-armed or dual-use.

These dangers will be heightened if either Russia or the United States overestimates the other’s current or future deployments of SLCMs or SLBGMs. This kind of threat inflation could result from the very real difficulties associated with estimating the current size of an adversary’s sea-based missile force—let alone its future size.

Estimating current SLCM deployments is challenging because modern vertical launching systems can accommodate various types of missiles, including air and missile defense interceptors and anti-ship and anti-submarine weapons, in addition to land-attack SLCMs. As a result, surface ships (and perhaps submarines) may carry fewer SLCMs than the maximum possible in order to facilitate the deployment of other kinds of weapons. The United States faces the additional challenge of estimating how many of Russia’s deployed SLCMs are nuclear-armed. Russia will face the same problem if the United States deploys nuclear-armed SLCMs of its own.

The challenges of estimating future deployments are even greater because states could change the number of SLCMs they deploy surreptitiously and relatively quickly. The probable deployment of nonnuclear SLBGMs, which will likely share a launching system with SLCMs and other missile types, will complicate matters further. There may also be uncertainty in each state’s estimates of how many ships the other is likely to deploy. To be sure, this uncertainty is limited by the difficulty of hiding shipbuilding activities and of changing construction plans. Even so, it could be significant, particularly four or five years into the future.

Of course, without access to both Russian and U.S. classified information, it is impossible to determine whether official deployment estimates are indeed prone to exaggeration. It is perhaps significant, however, that well-connected Russian experts have used estimates of the United States’ future force of “strategic conventional warheads”—including sea-based systems—that turned out to be inflated.⁵ If there is a similar bias in official Russian and U.S. estimates, then the resulting increase in danger is entirely unnecessary (unless it is the result of a deliberate policy of ambiguity in SLCM deployments, and there is no evidence that it is). Moscow and Washington, therefore, should have a shared interest in greater transparency.

Solution Concept

In theory, limiting SLCMs and SLBGMs in a follow-on to New START would be the optimal solution. However, the challenges to doing so would be insurmountable—with the sole exception of making nuclear-armed SLBGMs accountable.⁶ Given the military importance of nonnuclear SLCMs, in particular, neither the United States nor Russia would likely accept limits. Moreover, there would be daunting practical challenges. Most SLCMs are deployed on attack submarines and surface ships, and nonnuclear SLBGMs will likely be too. Neither Russia nor the United States has any interest in opening these vessels up to inspection.⁷

Ensuring transparency about current and planned future deployments of nuclear and nonnuclear SLCMs and nonnuclear SLBGMs is a more practical way forward.⁸ The proposed transparency arrangement outlined below is an expanded version of a U.S.-Soviet SLCM data exchange, which was negotiated as a side agreement to the Strategic Arms Reduction Treaty I (START I) and expired with that treaty in 2009.⁹

Verification

This proposed transparency arrangement, which would lack legally binding verification provisions, would probably not be as effective as a treaty in building confidence in the current and future size of SLCM and SLGBM forces. It would, however, represent a significant improvement over the status quo (no regulation at all).

Importantly, Russia and the United States would not need to take the exchanged information purely on the basis of trust. If intelligence information available to either participant confirmed at least some parts of the other’s declaration, without contradicting other parts, it would boost the credibility of the declaration as a whole. Discussions could help to address any concerns—though they would not be easy. If one participant had intelligence information suggesting the other’s declaration was incorrect, it might not be able to explain the basis for its concerns without compromising the sources and methods used to collect the intelligence. Nonetheless, a constructive dialogue might still be possible. For instance, a participant might be able to build confidence in the planned size of its future navy by providing unclassified information about shipbuilding plans and potentially even allowing occasional visits to shipbuilding facilities.

Assessment

Technical feasibility. From a technical perspective, the proposed transparency regime should be straightforward to negotiate and implement.

Political feasibility. Russia and the United States each have concerns about the other’s current and future forces of SLCMs and nonnuclear SLBGMs. They may each appreciate greater insight into the other’s force. Such transparency could also mitigate the risks that could be caused by potentially exaggerated deployment estimates. A secondary benefit for Moscow would be the possibility of using U.S. data to better estimate the number of Standard Missile-3 (SM-3) missile defense interceptors deployed on U.S. ships (those interceptors share launchers with SLCMs), thus helping to address Russian concerns about those interceptors. Although Russia has traditionally been skeptical of politically binding confidence-building measures, its participation in an earlier SLCM transparency arrangement sets a helpful precedent.

The primary political challenge to implementing this proposal would probably be the concern that exchanging classified data would undermine national security. The security risks, however, should be minimal. This proposal is narrowly tailored to mitigate one particular risk. It would not reveal a capability that was previously unknown to the other state or the precise mix of deployed weapon types—let alone the armaments on any particular ship. Therefore, unless either state seeks to use uncertainty about the scale of SLCM or SLBGM deployments to enhance deterrence, this data exchange should enhance the security of both states.

Notes

¹ Defense Intelligence Ballistic Missile Analysis Committee, “Ballistic and Cruise Missile Threat,” July 2020, 36, https://media.defense.gov/2021/Jan/11/2002563190/-1/-1/1/2020%20BALLISTIC%20AND%20CRUISE%20MISSILE%20THREAT_FINAL_2OCT_REDUCEDFILE.PDF.

² For a detailed review and critical assessment of Russian concerns, see Alexey Arbatov, Vladimir Dvorkin, and Petr Topychkanov, “Entanglement as a New Security Threat: A Russian Perspective” in Acton, ed., “Entanglement,” 24–31.

³ Indeed, first-generation U.S. SLBGMs will likely have shorter ranges than the most advanced contemporary SLCMs.

⁴ Kelley M. Sayler, “Hypersonic Weapons: Background and Issues for Congress,” R45811, Congressional Research Service, August 25, 2021, 4–6, https://fas.org/sgp/crs/weapons/R45811.pdf.

⁵ Alexey Arbatov, “Gambit or Endgame? The New State of Arms Control,” Carnegie Moscow Center, March 29, 2011, 21–22 and note 23, https://carnegieendowment.org/files/gambit_endgame.pdf.

⁶ Vaddi and Acton, “A ReSTART for U.S.-Russian Nuclear Arms Control,” 13–14.

⁷ The United States deploys some SLCMs on converted SSBNs, to which Russia is given limited inspection rights pursuant to New START.

⁸ The idea of a SLCM data exchange was revived in Jeffrey Lewis, “Russia and the United States Should Resume Data Exchanges on Nuclear-Armed Sea-Launched Cruise Missiles” in James M. Acton, ed., “Beyond Treaties: Immediate Steps to Reduce Nuclear Dangers,” Carnegie Endowment for International Peace, October 10, 2012, 4–5, https://carnegieendowment.org/files/beyond_treaties.pdf.

⁹ The United States and Russia also made a political commitment not to deploy more than 880 long-range nuclear-armed SLCMs. The text of the original data exchange has never been made public. A detailed description is available in U.S. Senate Committee on Foreign Relations, The START Treaty, S. HRG. 102-607, part 1, 102nd Cong, 2nd session, 1992, 436–437, https://books.google.com/books?id=gnpJAQAAIAAJ&printsec=frontcover#v=onepage&q&f=false.

The United States and NATO have various concerns about Russia’s large force of NSNWs, including the opacity surrounding those weapons’ locations. Consistent with Russian commitments under the 1991–1992 Presidential Nuclear Initiatives, Moscow has stated that the warheads for its NSNWs are “stored in centralized storage facilities,” which means that they are consolidated away from delivery systems (not that storage facilities are centrally located within Russia).¹ While the United States has not publicly disputed this claim, the exact locations of Russia’s nonstrategic nuclear warheads remain unverified.²

The United States’ only NSNWs are gravity bombs, which are reportedly held at six air bases in Europe and various additional locations in the United States.³ The U.S. government has never confirmed these locations—not least to avoid drawing public attention to weapons whose presence their host states’ populations generally oppose—and influential Russian analysts have sometimes expressed concern that U.S. nuclear gravity bombs may be stored at other European locations.

Russia may believe that ambiguity surrounding the locations of its NSNWs enhances its ability to deter NATO. Ambiguity, however, also creates real risks. NATO states, for example, have long been concerned about the possible presence of nonstrategic nuclear warheads in the Russian enclave of Kaliningrad.⁴ It remains unclear, however, whether the recently renovated storage facilities there currently house such warheads or whether Russia wants the option to introduce them at short notice.⁵ When coupled with associated concerns that Russia might use NSNWs early in a conflict, the possible presence of nuclear warheads in the enclave is threatening and exacerbates tensions—potentially unnecessarily if, in fact, no warheads are present.

Moreover, in a conventional conflict, ambiguity could prove escalatory. If NATO wrongly believed that nuclear warheads were present in Kaliningrad, it might attack warhead storage facilities and potential dual-use delivery systems to forestall Russian nuclear use. Moscow might then conclude that such attacks represented the start of a broader conventional campaign against Kaliningrad, which is surrounded by NATO states and could be difficult to defend with exclusively nonnuclear means. As a result, Moscow might resort to the very nuclear use that NATO had sought to forestall.

These risks underscore the value of a cooperative effort to reduce uncertainty and potential misperceptions about the locations of nonstrategic nuclear warheads. Specifically, the absence of warheads at empty actual or suspected storage facilities could be verified through inspections. In this context, “empty” connotes the absence of all nuclear warheads, regardless of type. (Because of the difficulty of distinguishing strategic from nonstrategic warheads, it would be infeasible to inspect facilities at which strategic warheads were present but nonstrategic ones were not.) The goal here would be to enhance transparency around a limited number of pairs of facilities—say, two to five—of particular concern to NATO or Russia, not to create a comprehensive verification regime intended to cover every facility that has stored warheads or could do so.

Inspections of empty storage facilities would also facilitate progress toward the long-term goal of a more comprehensive management regime for NSNWs—an idea long supported by Washington in one form or another.⁶ Such a regime, however, would face various practical difficulties, as U.S. officials have acknowledged in calling for Russia and the United States to undertake joint experiments to overcome verification obstacles.⁷ The inspections proposed here would contribute to the development of a verification regime for a treaty, say, that prohibited NSNWs from being located anywhere except declared facilities, or more ambitiously, one that imposed a single limit on all warheads—strategic and nonstrategic, regardless of their deployment status (see chapter 9). This latter concept would require counting nondeployed warheads inside storage facilities. Inspections of empty facilities would advance this goal by creating joint understandings about, for example, how to prevent inspectors from learning classified information about storage facilities (such as their security features) and how to reach agreement on which areas of military bases should be open for inspections.

Solution Concept

Inspections of actual or suspected warhead storage facilities—even empty ones—would represent a new frontier for arms control but would build on experience from previous agreements. Russia and the United States would first need to negotiate a generic verification protocol. Then to implement the protocol, NATO and Russia would have to negotiate and select pairs of sites—each pair containing one facility on NATO territory (including the United States) and one on Russian territory. Sites would be selected on the basis of mutual consent from Russia, the United States, and, in the case of a NATO facility located outside of the United States, the host state. Establishing an iterative process, in which lessons from each round of inspections were used to improve the generic verification protocol, would be particularly useful.

NATO has previously considered a similar concept and, as a first step, attempted to draw up a list of former warhead storage facilities that Russia could inspect (presumably on the basis of reciprocity). However, this process stalled amid bureaucratic and legal difficulties, including those created by many such facilities now being privately owned. The process proposed here would be simpler. NATO would not have to determine a comprehensive list of sites for inspection. Instead, it would have to assess the feasibility of inspections only at those sites of interest to Russia.

There would be some risk of nuclear warheads’ being removed from a facility in the time between facility selection and inspection—though the inspecting state would certainly monitor the facility closely with national technical means (NTM). While this risk would not be acceptable in a more comprehensive treaty, it should be tolerable in a politically binding confidence-building measure. In fact, this problem could be solved in a treaty with a provision that permitted inspectors to notify the host state of the inspection site only after their arrival in country, as is standard practice.

Verification

Baseline information exchange. A prerequisite to on-site inspections would be the exchange of baseline information about the selected facilities and the negotiation of site-specific implementation details. A key challenge here would be reaching agreement on the boundaries for inspection activities. Inspections would be feasible only if Russia and the United States could agree where nuclear warheads might conceivably be stored in a facility—thus precluding the need to inspect highly sensitive areas, such as communication centers, and avoiding very disruptive inspections of, for example, barracks or offices.

On-site inspections. The data exchange would enable each state to plan and conduct its inspection. One complication is the potential presence of weapon storage containers—whether empty storage containers for nuclear warheads or containers used to store nonnuclear munitions. Additionally, nonnuclear munitions outside of containers and other sensitive equipment, such as components for security systems, may also be present. The inspection protocol seeks to balance the intrusive access needed for credible verification with the protection of classified information that is not germane to the task of verifying the absence of nuclear warheads.

The protocol gives the host state the right to shroud any objects it deems to be sensitive. Meanwhile, it gives inspectors access rights to any location where a warhead could be hidden—as determined by the use of a cylindrical test object, representing the smallest plausible warhead storage container. If any warhead storage containers are present, inspectors may look inside to verify the absence of warheads (doing so should not reveal classified information unless a warhead is actually present in contravention of the state’s declaration). Inspectors can also use radiation detection equipment to verify that shrouded objects and storage containers for nonnuclear weapons do not contain nuclear material. Such technology has been used successfully pursuant to various previous U.S.-Russian arms control agreements. Its application here could be somewhat more challenging because undeclared nuclear warheads could be more heavily shielded in storage than when deployed on delivery systems. On paper, this problem could be addressed by increasing the detection time—an issue that Russia and the United States could jointly consider while negotiating the generic verification protocol.

Assessment

Technical feasibility. In crafting a verification protocol, Russia and the United States could draw upon their considerable experience of conducting inspections at sensitive facilities and using radiation detection equipment for verification purposes. Moreover, they would not have to address the various complications associated with inspecting facilities at which nuclear warheads are present. Yet significant challenges—such as the need to agree on inspection boundaries—would remain. These challenges appear manageable, but the only way to know for sure would be for Russia and the United States to try to negotiate and implement the proposed agreement.

Political feasibility. The United States and its NATO allies have clear concerns about the locations of Russia’s nonstrategic nuclear warheads. And there is some evidence that these concerns are reciprocal.¹⁰ But even if Moscow does not currently have concerns about the locations of U.S. NSNWs in Europe, it could easily become concerned in the context of a reinvigorated arms race. Therefore, all states would benefit directly from enhanced transparency. This proposal would benefit the United States and NATO more than Russia, however, and so it would likely need to be paired with a measure of more interest to Russia—perhaps the confidence-building regime for Aegis Ashore launchers in Europe (see chapter 3).

At least three other political challenges could also arise. First, the proposed agreement may go too far for Russia and not far enough for the United States. The United States seeks a comprehensive regime for managing NSNWs. However, Moscow has repeatedly rejected this concept; indeed, it appears to be sticking to its long-standing position that U.S. nuclear weapons based in Europe must be returned to the United States and their storage infrastructure permanently dismantled before negotiations on limiting NSNWs can begin.¹¹ This proposal could help to break the logjam. It would not require negotiations over limits on NSNWs but would build experience and confidence in inspecting warhead storage facilities, thus making progress toward the goal of a more comprehensive treaty.

Second, it could be challenging for Russia and the United States to select facilities for inspection. There would presumably be some empty actual or suspected warhead storage facilities at which an inspection request could not be accommodated; some are likely too sensitive, and others, such as former warhead storage facilities now in private hands, may present insurmountable bureaucratic and legal difficulties. Because facilities must be selected by mutual consent, the host state could always veto an inspection request. This veto power represents an important safeguard—though if it were used too often, the proposed agreement would likely fall apart amid reciprocal accusations of bad faith.

Finally, inspections in Europe could create particular legal, diplomatic, and political complications. While navigating these difficulties would not be entirely straightforward, they were successfully tackled in implementing the INF Treaty, which suggests that they should not be insurmountable.

Notes

¹ Russian Federation, “Practical Steps of the Russian Federation Towards Nuclear Disarmament,” 2015 Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons, New York, April 27–May 22, 2015, 20, http://www.pircenter.org/media/content/files/13/14319751051.pdf.

² U.S. Department of State, “Adherence to and Compliance With Arms Control, Nonproliferation, and Disarmament Agreements and Commitments,” 12.

³ Kristensen and Korda, “United States Nuclear Weapons, 2020,” 56.

⁴ Hans M. Kristensen, “Non-Strategic Nuclear Weapons,” Special Report 3, Federation of American Scientists, May 2012, 70-75, https://fas.org/_docs/Non_Strategic_Nuclear_Weapons.pdf.

⁵ Hans M. Kristensen, “Russia Upgrades Nuclear Weapons Storage Site in Kaliningrad,” Strategic Security (blog), June 18, 2018, https://fas.org/blogs/security/2018/06/kaliningrad.

⁶ U.S. Department of State, Office of the Spokesperson, “Secretary Blinken’s Call With Russian Foreign Minister Lavrov,” February 4, 2021, https://www.state.gov/secretary-blinkens-call-with-russian-foreign-minister-lavrov/.

⁷ U.S. Department of State, “Briefing With Ambassador Marshall Billingslea, U.S. Special Presidential Envoy for Arms Control and Lt. Gen. Thomas Bussiere, Deputy Commander of the U.S. Strategic Command,” August 18, 2020, https://2017-2021.state.gov/press-briefing-with-ambassador-marshall-billingslea-u-s-special-presidential-envoy-for-arms-control-and-lt-gen-thomas-bussiere-deputy-commander-of-the-u-s-strategic-command/index.html.

⁸ This definition would include, for example, underground weapon storage vaults.

⁹ These dimensions are illustrative. The dimensions of the test object should be based on intelligence information about the size of actual warhead storage containers. For a rough precedent for the use of a template, see Joseph P. Harahan, On-Site Inspections Under the INF Treaty: A History of the On-Site Inspection Agency and INF Treaty Implementation, 1988–1991 (Washington, DC: U.S. Department of Defense, On-Site Inspection Agency, 1993), 82, https://www.dtra.mil/Portals/61/Documents/History/On-Site%20Inspections%20INF%20Treaty-opt.pdf.

¹⁰ Personal communication, Russian analyst, 2013.

¹¹ Ministry of Foreign Affairs of the Russian Federation, “Deputy Foreign Minister Sergey Ryabkov’s Interview With the Newspaper Kommersant,” September 22, 2020, https://www.mid.ru/en/foreign_policy/news/-/asset_publisher/cKNonkJE02Bw/content/id/4348327. Ryabkov’s comments about negotiations over NSNWs were slightly ambiguous—hence the phrase “appears to be sticking.”

Within the broader U.S.-Russian dispute over missile defense, a particular point of contention is the United States’ European Phased Adaptive Approach (EPAA). This initiative seeks to defend NATO against Iran.¹ To this end, the United States has deployed SM-3 Block IB interceptors in Romania. It now plans to deploy more capable SM-3 Block IIA interceptors at the same site and at a second site in Poland. The launchers at each of these Aegis Ashore installations are adapted from the U.S. Navy’s MK-41 Vertical Launching System, which is used on ships equipped with the Aegis air and missile defense system to launch SLCMs and other missiles as well as SM-3 interceptors.

Russia believes that the EPAA may threaten its ability to target the United States with ICBMs. The United States’ November 2020 test of an SM-3 Block IIA interceptor against an ICBM-class target has added to Moscow’s unease.² The U.S. Department of Defense contends that this interceptor “has the potential” to contribute to the defense of the homeland against “rogue states’” ICBMs, which have less capability to penetrate defenses than Russian ICBMs.³ Moreover, to be useful for homeland defense, SM-3 Block IIA interceptors would need to be deployed near the United States; systems located in Europe would be unable to catch a Russian ICBM. These considerations do not seem to have assured Moscow, however, which may have overestimated the capabilities of the SM-3 interceptor—in particular, its burnout speed (that is, its maximum speed, which is reached immediately after its motors have ceased firing).

Russia’s concerns about the EPAA extend beyond the interception of its ICBMs to the possibility that the launchers could be used to fire offensive missiles, particularly cruise missiles. In response, the U.S. Department of State has indicated that the “Aegis Ashore Missile Defense System” (a term that appears to include more than just the launchers themselves) “lacks the software, fire control hardware, support equipment, and other infrastructure” required for launching offensive missiles.⁴ It has also stated that “the defensive nature of the Aegis Ashore sites is documented in U.S. basing agreements” with Poland and Romania.⁵ Russia has made clear that it places little value on these assurances, noting, for example, that the United States has conducted a test launch of a cruise missile from a land-based MK-41 test launcher.⁶

The United States and its NATO allies have compelling reasons to try to address Russia’s concerns. Most importantly, such concerns could spark inadvertent escalation. Moscow has threatened to attack Aegis Ashore installations preemptively in a crisis or conflict—presumably both to ensure the effectiveness of its nuclear deterrent and to prevent cruise missile attacks that could undermine its ability to wage a conventional war.⁷ Meanwhile, in peacetime, Russian concerns complicate the development of arms control agreements, including measures to manage the Poseidon torpedo and Burevestnik cruise missile, which Russia is developing to penetrate U.S. missile defenses. Indeed, if Russian concerns about missile defense are not successfully managed, Moscow may take further countermeasures—such as the expansion of its strategic nuclear forces or the development of additional kinds of exotic strategic delivery systems—adding yet more fuel to the incipient arms race.

Solution Concept

Efforts to manage the dispute over Aegis Ashore should focus on the development of a transparency regime to demonstrate that (1) SM-3 interceptors located in Europe cannot threaten Russian ICBMs because they have insufficient burnout speed and (2) European Aegis Ashore installations cannot launch offensive missiles or do not contain missiles other than SM-3 interceptors. Successfully implementing this regime would not resolve the entire missile defense dispute or even address all of Russia’s concerns about the EPAA.⁸ However, it would ameliorate an acute part of the problem and could also catalyze a process for managing other Russian and U.S. concerns. Washington could indicate that if the transparency regime for Aegis Ashore installations is implemented successfully and if Russia starts to address U.S. concerns on NSNWs—by, for example, agreeing to inspections of empty warhead storage facilities (see chapter 2)—then the United States will be willing to negotiate additional steps to manage the missile defense dispute.

In 2011, the administration of then U.S. president Barack Obama invited Russia to measure an SM-3 interceptor’s burnout speed—though the proposal appeared to apply to just one flight test.⁹ Moscow rejected that overture as “propagandistic.”¹⁰ The current proposal will hopefully be more attractive because it is more comprehensive. It would apply to each interceptor type that has been or will be deployed in Europe unless its burnout speed is lower than 3 kilometers per second, in which case it could not meaningfully contribute to strategic missile defense operations—as Russia and the United States previously agreed.¹¹ Meanwhile, the confidence-building measures relating to offensive missiles aim to operationalize U.S. commitments already made to Poland and Romania about the exclusively defensive purpose of Aegis Ashore installations.

Verification

Interceptor burnout speed. The United States generally conducts interceptor flight tests from the Pacific Missile Range Facility in Hawaii. Russia could use its missile range instrumentation ship, the Marshal Krylov, to measure the interceptor’s burnout speed.¹² Given that this ship’s radar likely has a range in excess of 600 kilometers, the vessel could be positioned on the high seas (that is, in international waters) at a site of Russia’s choosing. As such, Russia does not actually need an invitation to monitor U.S. interceptor flight tests—though cooperation would have two advantages. First, the United States would inform Russia of the test in advance, giving it time to position the ship. Second, the United States would commit not to interfere with Russian measurements of the interceptor’s speed.

Exclusively defensive purpose of European Aegis Ashore installations. The first step in developing any verification approach would be meetings between U.S. and Russian officials, including technical experts, so that the United States could identify some or all of the “fire control hardware, support equipment, and other infrastructure” that is missing from European Aegis Ashore installations and thus renders them incapable of launching cruise missiles.¹³ As part of this process, the United States should provide Russia with commercial satellite imagery and internal and external photographs that highlight differences between Aegis Ashore installations and their sea-based equivalents. The United States could also consider offering Russia a one-off exhibition of the land-based MK-41 test launcher in California—which has been used to launch a cruise missile—and, with the host state’s permission, an Aegis Ashore installation in Europe.

The confidence-building measures relating to offensive missiles aim to operationalize U.S. commitments already made to Poland and Romania about the exclusively defensive purpose of Aegis Ashore installations.

Based on this information, the two sides should then attempt to jointly identify externally observable distinguishing features (EODFs) between the land- and sea-based launchers. The outcome of this exercise would determine the optimal verification approach.

The most straightforward case would arise if the two sides jointly identified EODFs that could be detected with satellite imagery. Verification could then be facilitated by a U.S. commitment not to interfere with Russian NTM—a common feature of many arms control agreements that might be generally helpful in addressing Russian concerns about the EPAA.

A second possibility is that EODFs are identified but are visible only from the ground. In this scenario, periodic on-site inspections, with the host nation’s consent, would be needed so Russian inspectors could verify the absence of one or more components needed to launch cruise missiles.

The third and most challenging case would arise if the United States and Russia were unable to jointly identify any EODFs. The most direct approach to verification would then be for the United States to permit Russian inspectors to periodically select and view the inside of an agreed number of Aegis Ashore launchers to check that they are loaded with missile defense interceptors and not cruise missiles (similar to inspections of the missiles inside ICBM silos or SSBN launch tubes pursuant to New START). To facilitate such inspections, which would again require the host government’s consent, the United States should provide Russia with identifying characteristics for each type of missile defense interceptor deployed in European Aegis Ashore launchers (fortunately, SM-3 interceptors look very different from Tomahawk cruise missiles).

Under any scenario, Russia could use NTM to try to detect the loading of offensive missiles into launchers. It therefore could be helpful for U.S. technical experts to explain to their Russian counterparts how the loading of interceptors and offensive missiles can be distinguished—if indeed they can. Such cooperation would be particularly important if Russia and the United States failed to identify any EODFs and if the United States was unwilling to allow Russian inspectors to view the interceptors inside launchers. In this case, to enhance Russia’s ability to detect any loading of offensive missiles, the United States could (1) permit Russian inspectors to install and use remote monitoring video equipment so Russia could continuously observe specified areas of European Aegis Ashore installations and (2) commit to notifying Russia at least twenty-four hours in advance of the loading or unloading of European Aegis Ashore launchers so it has time to make any necessary preparations for observing the process with NTM.

On-site access of any kind would require Russia and the United States to negotiate a politically binding verification protocol. From a U.S. perspective, a key consideration would be ensuring that Russian inspectors could not learn classified information other than that officially disclosed pursuant to the inspection agreement. To this end, the shrouding of equipment not subject to inspection could be helpful. A separate agreement between the United States and each host nation would also be needed.

Assessment

Technical feasibility. Designing a regime to verify the exclusively defensive nature of Aegis Ashore installations could prove tricky. The primary challenge would probably be the joint identification of EODFs—an issue that Russia and the United States have frequently disagreed on in other contexts. If the two states failed to agree on EODFs, it might nonetheless be possible for Russia to ascertain that the launchers are configured for defensive purposes by verifying they are loaded with interceptors and not cruise missiles.

Measuring the burnout speed of an interceptor should be straightforward for Russia, which would rely on its own equipment. This speed is probably the single most important parameter for determining the extent of any threat posed by European Aegis Ashore installations to Russian ICBMs—but it is not the only one. As a result, Russia’s gaining confidence in this speed should reduce the scope for disagreement between Moscow and Washington but might not eliminate it entirely. Therefore, this proposal would be best implemented as part of a broader U.S.-Russian dialogue over missile defense, in which the two sides could discuss how to determine whether defenses threaten ICBMs.

Political feasibility. This proposed measure is intended to address Russian concerns and should be paired with one to address U.S. concerns, such as inspections of empty warhead storage facilities (see chapter 2). Even if it is, however, the proposal would stir up controversy within both the United States and NATO. Domestic critics would probably argue, as they did in 2011, that permitting Russia to measure the burnout speed of a U.S. interceptor would disclose classified information that could compromise national security. Yet, as the Obama administration concluded back then, this information would not meaningfully help Russia (or any third party to which Russia disclosed this information) to defeat U.S. defenses. Critically, to protect against Russia’s learning much more sensitive information (such as the performance of the interceptor’s sensors), the United States could continue to use denial and deception techniques (such as the encryption of telemetry data) that did not interfere with Russian speed measurements. Meanwhile, orchestrating Russian inspections on the territory of a U.S. ally would be politically sensitive, but, as history demonstrates, hardly infeasible.

All these difficulties, however, pale compared to the long-standing acrimony between Russia and the United States on missile defense. The two states have long approached this issue with seemingly irreconcilable positions. Moscow has demanded legally binding guarantees without giving any indication that it is willing to offer the United States anything in return. Washington has insisted that it can offer nothing more than politically binding confidence-building measures—that is, when it is prepared to engage at all.

Today, however, there is an opening for progress, albeit a slight one. Russian officials have indicated a new willingness to consider politically binding confidence-building measures. The Biden administration, meanwhile, appears to be more willing than its predecessor to try to address Russian concerns. To improve the prospects for progress, Washington should frame this proposal as the first step in a long-term process to address a wider range of concerns that could potentially include the development of legally binding instruments. In this spirit, this proposal would not be a one-off exercise; it would permit Russia to measure the burnout speed of each interceptor type deployed in Europe and would provide Russia with an ongoing and verified commitment about the exclusively defensive purpose of European Aegis Ashore installations.

Notes

¹ U.S. Department of Defense, “Missile Defense Review,” 2019, 69, https://media.defense.gov/2019/Jan/17/2002080666/-1/-1/1/2019-MISSILE-DEFENSE-REVIEW.pdf.

² Ministry of Foreign Affairs of the Russian Federation, “Briefing by Foreign Ministry Spokeswoman Maria Zakharova,” Moscow, November 19, 2020, https://www.mid.ru/en/press_service/spokesman/briefings/-/asset_publisher/D2wHaWMCU6Od/content/id/4443750.

³ U.S. Department of Defense, “Missile Defense Review,” 55.

⁴ U.S. Department of State, Bureau of Arms Control, Verification and Compliance, “Refuting Russian Allegations of U.S. Noncompliance With the INF Treaty,” fact sheet, December 8, 2017, https://2017-2021.state.gov/refuting-russian-allegations-of-u-s-noncompliance-with-the-inf-treaty/index.html.

⁵ Ibid.

⁶ President of Russia, transcript of “Meeting With Permanent Members of the Security Council,” August 23, 2019, The Kremlin, Moscow, http://en.kremlin.ru/events/president/news/61359.

⁷ Andrew E. Kramer, “Russian General Makes Threat on Missile-Defense Sites,” New York Times, May 3, 2012, https://www.nytimes.com/2012/05/04/world/europe/russian-general-threatens-pre-emptive-attacks-on-missile-defense-sites.html.

⁸ Additionally, Russian officials have expressed concerns that the United States may convert European missile defense interceptors into land-attack ballistic missiles. See U.S. Department of Defense, transcript of “DoD News Briefing With Secretary Gates and Gen. Cartwright From the Pentagon,” September 17, 2009, https://web.archive.org/web/20191119150130/https://archive.defense.gov/transcripts/transcript.aspx?transcriptid=4479. See chapter 8 for a proposal to help address this issue. Separately, the United States could commit to not testing any type of missile defense interceptor located in Europe against a land-based target.

⁹ Susan Cornwell and Jim Wolf, “U.S. Invites Russia to Measure Missile-Defense Test,” Reuters, October 18, 2011, https://www.reuters.com/article/russia-usa-missiles/u-s-invites-russia-to-measure-missile-defense-test-idUSN1E79H18N20111018.

¹⁰ “Russia Dismisses U.S. Antimissile Test Proposal as Propaganda,” Nuclear Threat Initiative, November 9, 2011, available at https://web.archive.org/web/20210625033632/https://www.nti.org/gsn/article/russia-dismisses-us-antimissile-test-proposal-as-propaganda/.

¹¹ Amy F. Woolf, “Anti-Ballistic Missile Treaty Demarcation and Succession Agreements: Background and Issues,” 98-946F, Congressional Research Service, April 27, 2000, 17, https://www.everycrsreport.com/files/20000427_98-496F_85d66fc81845bb0482f3d18ede25f07a8a66f0d3.pdf.

¹² “Upgraded Missile Range Instrumentation Ship to Support Launches at Vostochny Cosmodrome,” TASS, September 16, 2015, https://tass.com/science/821547.

¹³ U.S. Department of State, Bureau of Arms Control, Verification and Compliance, “Refuting Russian Allegations of U.S. Noncompliance With the INF Treaty.”

As China expands its nuclear forces—a process that the U.S. government expects to continue—a broad consensus within the U.S. national security community about the importance of engaging China in arms control has emerged. The administration of U.S. president Donald Trump unsuccessfully sought to engage China and Russia in negotiations toward a trilateral treaty.¹ The Biden administration has indicated it will seek to engage China and Russia separately. However, in public at least, it has not yet made any specific proposals for bilateral U.S.-Chinese arms control measures but instead has called generally for the two states to pursue “practical measures to reduce the risks of destabilizing arms races.”²

Beijing, meanwhile, has consistently rebuffed the United States’ entreaties, suggesting—without committing—that it will join multilateral disarmament negotiations only after the United States has reduced its nuclear arsenal to close the “huge gap” with China.³ Beijing has various concerns about engaging in arms control, but an important one is likely that verification might undermine the survivability of China’s nuclear forces by revealing sensitive information about them—the location of individual weapons, in particular.⁴

The United States cannot force China to negotiate. The Trump administration succeeded in demonstrating this lack of leverage through its fruitless call for Moscow to “bring China to the negotiating table,” and its discussion of conducting a nuclear test to pressure Beijing (a step that would likely have ended up fueling arms racing).⁵ Instead, if Washington is to have any chance of engaging China in arms control, it will have to craft proposals that mitigate Chinese concerns about transparency, while also identifying suitably valuable American concessions that could form part of a mutually beneficial quid pro quo. (China should undertake such thinking too as a good-faith effort to comply with Article VI of the Nuclear Non-Proliferation Treaty; as a practical matter, however, since it is the United States that wants to engage China, it is going to be up to Washington to work out how to entice Beijing to the negotiating table.)

Against this background, limits on warheads or even missiles would be a nonstarter. The limiting of launchers and bombers (see chapter 8) would be more viable, though is still an ambitious, long-term goal. For the time being, the most promising, albeit still challenging, approach is to focus on fissile material—the separated plutonium and highly enriched uranium (HEU) needed to produce nuclear warheads.

If China seeks to build up its nuclear forces to the point where they rival the United States’ arsenal in size, it will have to manufacture more than 3,000 additional nuclear warheads. According to the U.S. Defense Intelligence Agency, however, even if China converted all its available fissile material into nuclear weapons, its arsenal would still comprise only several hundred warheads (perhaps double its current stockpile).⁶ As a result, U.S. concerns about a Chinese nuclear buildup could be addressed by seeking to prevent any new production of fissile material.

Solution Concept

China and the United States should jointly declare a cutoff in fissile material production and adopt transparency measures to enhance this cutoff’s credibility. Ideally, the cutoff would extend to all fissile material production. In the real world, a more plausible approach would be for China and the United States to agree not to produce any more fissile material for military purposes and to place all newly produced civil material under International Atomic Energy Agency (IAEA) safeguards.

The United States unilaterally ceased the production of fissile material for any purpose, civil or military, almost thirty years ago and has no plans to restart it (indeed, it could expand its arsenal dramatically without doing so). It also published comprehensive declarations of its plutonium and HEU stockpiles in the mid-1990s—though has provided only one update (to the HEU declaration) since.⁷

There are widespread reports that China has ceased the production of weapon-usable fissile material for military purposes.⁸ However, Beijing has never officially confirmed them—possibly because it wants to retain the option of producing more such material.

China has ambitious plans to develop a civil reprocessing program.⁹ Its only existing civil reprocessing facility, a pilot plant with a small throughput, is probably no longer operational—though there is uncertainty here because, starting in 2018, China ceased to submit updates on its civil plutonium stockpile to a voluntary IAEA transparency initiative known as INFCIRC/549 (the United States remains an active participant).¹⁰ China is currently constructing one “demonstration” reprocessing plant and appears to be starting work on a second.¹¹ Over the longer term, it aims to develop one or more industrial-scale facilities.

There is now growing concern within the United States that plutonium separated in these plants may be diverted for use in China’s nuclear weapons program. This concern has been fueled by China’s ambitious nuclear modernization efforts and by its plans to develop so-called fast reactors that will (if they can be made to work) produce plutonium particularly suitable for use in nuclear warheads. Given China is unlikely to relinquish its reprocessing program, a commitment to allow the IAEA to safeguard all newly produced civil fissile material could be the basis for a compromise.

The fissile material declarations are a confidence-building measure intended to complement the cutoff by providing comprehensive and regularly updated information about each state’s fissile material stockpiles. They would build on the United States’ previous voluntary declarations and on the information about civil fissile material that the United States makes available through INFCIRC/549 and that China used to make available through that same mechanism.

Verification

After committing to a bilateral cutoff in the production of weapon-usable fissile material, China and the United States should discuss any compliance concerns, with the aim of developing ad hoc verification measures to alleviate those specific concerns.

Verifying a cutoff in plutonium production should be unproblematic. The United States surely already uses NTM to monitor the nonoperational status of China’s military plutonium-production program. Similarly, China must use NTM to verify that U.S. military plutonium-production reactors and reprocessing plants are being decommissioned.¹²

Verifying a cutoff in HEU production could be slightly more challenging. China and the United States operate civil enrichment facilities to produce low enriched uranium, primarily for nuclear power reactors.¹³ However, all these facilities are technically capable of producing HEU, and China’s Heping facility—in which HEU for nuclear weapons was produced—may currently produce HEU for research reactors.¹⁴ If so, under a cutoff, such production would have to cease or be placed under IAEA safeguards.

Confirming the nonproduction of HEU at enrichment facilities would require physical access, which, to be politically palatable, would have to be reciprocal. While inspections conducted by either the IAEA or national inspectors would be intrusive, there would be few technical difficulties.

To verify that HEU is not being produced in an operational enrichment plant that has never produced such material, swipe samples could be taken and analyzed to confirm the absence of HEU particles. If such a plant has produced HEU, it might be possible to check that production has ceased by determining the minimum age of HEU particles.¹⁵ Failing that, the enrichment level of product streams could be measured through online enrichment monitors or periodic sampling. Finally, if either state were concerned that the other had built a secret enrichment plant to produce HEU for military purposes, swipe samples could again be used to confirm the absence of HEU particles at the suspect facility (if needed, the host state could use extensive shrouding to protect unrelated classified information).

In contrast to verifying a cutoff, the comprehensive verification of stockpile declarations would be functionally impossible. One reason is that classification rules around weapon components would prevent inspectors from measuring their fissile material content. That said, each state could compare the other’s declarations to its own intelligence estimates and commit to discussing inconsistencies. In particular, the past production of fissile material would be a less sensitive subject than its subsequent use or current disposition. It might therefore be possible to address discrepancies over production by being transparent about the operational histories of relevant facilities and by potentially using nuclear archeology (which involves analyzing components in facilities and waste streams to estimate past production).

Assessment

Technical feasibility. Verifying a cutoff should be relatively straightforward, even if potentially intrusive. By contrast, verifying stockpile declarations, at least in any comprehensive way, would be impossible. Ultimately, China and the United States would have to decide whether or not they were better off receiving additional information, even if they could not verify it.

Political feasibility. This proposal would benefit the United States more than China—at least if implemented by itself. The United States has far more fissile material for nuclear weapons than it has use for, even though production ceased almost three decades ago. China, by contrast, has a much smaller stockpile, and while Beijing may not be producing more fissile material for nuclear weapons right now, it probably wants to maintain the option to do so. Indeed, China is probably quite pleased that Pakistan has blocked negotiations over a multilateral fissile material cutoff treaty, even if Beijing pays lip service to the goal of concluding such an agreement.¹⁶ In some ways, a bilateral agreement with the United States may be more problematic for Beijing than a multilateral treaty because it would not cover all the other countries that affect China’s fissile material requirements (namely, India, Russia, and perhaps even Japan). Nonetheless, Beijing has three potential motivations to explore this proposal.

Beijing may be reluctant to abandon the option of producing more fissile material because it is concerned about the survivability of its nuclear forces and believes it may need to manufacture more nuclear warheads in the future.

First, in practice, the proposed measure would not be implemented by itself. Inevitably, it would have to be adopted as part of a mutually beneficial package that required the United States to make significant concessions. To facilitate negotiations over such a package, Beijing should start considering what it would ask of Washington. Meanwhile, U.S. and Chinese experts could explore the trade space informally.

Beijing may be reluctant to abandon the option of producing more fissile material because it is concerned about the survivability of its nuclear forces and believes it may need to manufacture more nuclear warheads in the future. Chinese concerns on this score are driven, in no small part, by U.S. ballistic missile defense programs. At least in theory, space-based missile defenses would provide the most plausible means for the United States to undermine China’s nuclear deterrent and are a source of acute concern for Chinese experts.¹⁷ So, at the same time that China and the United States agreed to a politically binding cutoff in fissile material production, they could also agree, on a politically binding basis again, not to test or deploy space-based missile defenses. Such an agreement would be a step toward a legally binding trilateral prohibition (see chapter 7).

Second, in private, some Chinese officials and experts question the accuracy of the United States’ fissile material declarations. This proposal would help China gain deeper insight into the U.S. stockpile.

Third, while fissile material is unquestionably a sensitive issue for Beijing, this proposal would presumably be more acceptable to China than many, if not all, of the alternatives—binding limits on nuclear forces, in particular. Such limits would reveal the exact size of China’s nuclear arsenal and the locations of its weapons, exacerbating Beijing’s concerns about their vulnerability. By contrast, stockpile declarations would reveal only an approximate maximum size of China’s nuclear arsenal and nothing about weapon locations. To be sure, Beijing does not need to choose any of the alternatives; it could simply continue not to engage. Yet Chinese leaders should ponder the advice of the scholar Tong Zhao, who has argued that arms control could enhance China’s interests by preventing dangerously destructive competition with the United States, by bolstering China’s image as a responsible power, and by reducing defense spending.¹⁸ If those leaders agree with this argument in principle, this proposal could be part of a practical way forward.

Notes

¹ “Trump Calls for Arms Control With Russia and China in Putin Call,” Reuters, May 7, 2020, https://www.reuters.com/article/us-usa-trump-russia/trump-stresses-desire-for-arms-control-with-russia-china-in-putin-call-idUSKBN22J2GT.

² Ned Price, “Department Press Briefing—July 1, 2021,” U.S. Department of State, https://www.state.gov/briefings/department-press-briefing-july-1-2021/.

³ Ministry of Foreign Affairs of the People’s Republic of China, “Department of Arms Control and Disarmament Holds Briefing for International Arms Control and Disarmament Issues.”

⁴ Wu Riqiang, “How China Practices and Thinks About Nuclear Transparency” in Li Bin and Tong Zhao, eds., “Understanding Chinese Nuclear Thinking,” Carnegie Endowment for International Peace, October 28, 2016, especially 237–239, https://carnegieendowment.org/files/ChineseNuclearThinking_Final.pdf.

⁵ “Special Presidential Envoy Marshall Billingslea on the Future of Nuclear Arms Control,” Hudson Institute, May 21, 2020, 3, https://s3.amazonaws.com/media.hudson.org/Transcript_Marshall%20Billingslea%20on%20the%20Future%20of%20Nuclear%20Arms%20Control.pdf; and John Hudson and Paul Sonne, “Trump Administration Discussed Conducting First U.S. Nuclear Test in Decades,” Washington Post, May 22, 2020, https://www.washingtonpost.com/national-security/trump-administration-discussed-conducting-first-us-nuclear-test-in-decades/2020/05/22/a805c904-9c5b-11ea-b60c-3be060a4f8e1_story.html.

⁶ U.S.-China Economic and Security Review Commission, “Hearing on a ‘World-Class’ Military: Assessing China’s Global Military Ambitions,” Washington, DC, June 20, 2019, 35, https://www.uscc.gov/sites/default/files/2019-10/June%2020,%202019%20Hearing%20Transcript.pdf.

⁷ “Global Fissile Material Report 2010: Balancing the Books: Production and Stocks,” International Panel on Fissile Materials, 2010, note 109, http://fissilematerials.org/library/gfmr10.pdf.

⁸ For example, Hui Zhang, “China’s Fissile Material Production and Stockpile,” Research Report No. 17, International Panel on Fissile Materials, 2017, http://fissilematerials.org/library/rr17.pdf. China reportedly fuels its naval reactors with low enriched uranium. See Hui Zhang, “Chinese Naval Reactors,” IPFM Blog (blog), May 10, 2017, http://fissilematerials.org/blog/2017/05/chinese_naval_reactors.html.

⁹ Hui Zhang, “China Is Speeding Up Its Plutonium Recycling Programs,” Bulletin of the Atomic Scientists 76, no. 4 (2020): 210–216; and “China’s Nuclear Fuel Cycle,” World Nuclear Association, August 2021, https://www.world-nuclear.org/information-library/country-profiles/countries-a-f/china-nuclear-fuel-cycle.aspx.

¹⁰ International Atomic Energy Agency, “Communication Received From Certain Member States Concerning Their Policies Regarding the Management of Plutonium,” March 16, 1998, last updated October 15, 2021, https://www.iaea.org/publications/documents/infcircs/communication-received-certain-member-states-concerning-their-policies-regarding-management-plutonium.

¹¹ Hui Zhang, “China Starts Construction of a Second 200 MT/Year Reprocessing Plant,” IPFM Blog (blog), March 21, 2021, http://fissilematerials.org/blog/2021/03/china_starts_construction.html.

¹² The H Canyon at the Savannah River Plant is probably capable of extracting small quantities of plutonium from spent fuel, but it has never been used for this purpose. See “H Area Nuclear Materials Disposition,” Savannah River Site, https://www.srs.gov/general/programs/harea/index.htm.

¹³ “China’s Nuclear Fuel Cycle”; and “US Nuclear Fuel Cycle,” World Nuclear Association, May 2021, https://www.world-nuclear.org/information-library/country-profiles/countries-t-z/usa-nuclear-fuel-cycle.aspx. Parts of one Chinese facility are under IAEA safeguards. The U.S. enrichment facility was offered for, but is not under, safeguards.

¹⁴ Zhang, “China’s Fissile Material Production and Stockpile,” 12–13. Additionally, both China and the United States have shut down gaseous diffusion enrichment plants. NTM should be adequate for monitoring their status.

¹⁵ “Global Fissile Material Report 2008: Scope and Verification of a Fissile Material (Cutoff) Treaty,” International Panel on Fissile Materials, 2008, 48–49, http://fissilematerials.org/library/gfmr08.pdf.

¹⁶ Bates Gill, “China and Nuclear Arms Control: Current Positions and Future Policies,” SIPRI Insights on Peace and Security, no. 2010/4, Stockholm International Peace Research Institute (SIPRI), April 2010, 8–9, https://www.sipri.org/sites/default/files/files/insight/SIPRIInsight1004.pdf.

¹⁷ Zhao, “Narrowing the U.S.-China Gap on Missile Defense,” 33–34.

¹⁸ Tong Zhao, “Opportunities for Nuclear Arms Control Engagement With China,” Arms Control Today, January/February 2020, https://www.armscontrol.org/act/2020-01/features/opportunities-nuclear-arms-control-engagement-china.

If mistaken for an attack, a ballistic missile test, missile defense test, or space launch could spark escalation. This risk is not hypothetical. In January 1995, Russia mistook a sounding rocket launched off the Norwegian coast for a U.S. nuclear-armed ballistic missile. Because Moscow feared that the first wave of a U.S. campaign to destroy its nuclear forces might comprise a small number of ballistic missiles—perhaps just one—fired against key command-and-control nodes, the result was a cascade of warnings that reached Russian president Boris Yeltsin within four minutes.¹ Only after he activated his “nuclear briefcase” and ordered the Strategic Rocket Force to prepare to launch ICBMs did the Russian military determine that the launch was benign.

Twenty-five years later, notwithstanding subsequent improvements in Russia’s early-warning capabilities, there remains a real risk that escalation could result from either a mischaracterized launch or, relatedly, from preparations for a test launch being mistaken as preparations for an attack—a scenario that would invite a preemptive strike against the launch site. There are two reasons to take these dangers seriously.

First, while the risks of escalation may be low in peacetime, they could rise significantly at times of heightened tensions. During such periods, national and military leaders might be more inclined to interpret an ambiguous event in the worst possible light because they were expecting or, at least, were concerned about an attack.² Moreover, a state that feared that an attack might be underway or imminent would be more likely to respond precipitously in a crisis than in peacetime. Second, currently, the danger of inadvertent escalation resulting from a test or space launch (or its preparations) would be limited to a crisis involving Russia and the United States because they are the only two states with the capability to detect a ballistic missile attack and launch some of their own nuclear forces before the incoming weapons had detonated. China, however, is now acquiring a similar launch-under-attack capability, creating the possibility that these dangers could soon arise in a U.S.-Chinese crisis too.

Notifications before test or space launches can help reduce these risks. There are two operative notification agreements involving Russia and the United States: the 1988 U.S.-Soviet Ballistic Missile Launch Notification Agreement, which was made legally binding through its incorporation into New START, and the multilateral 2002 Hague Code of Conduct Against Ballistic Missile Proliferation, a politically binding document that calls for notifications of space launches (among many other provisions). Separately, in 2009, China and Russia concluded their own legally binding notification arrangement, the Agreement on Notifications of Launches of Ballistic Missiles and Space Launch Vehicles, which was extended in 2020 for ten years.³ (See table 1 for a comparison of the notification commitments.)

This patchwork of agreements has five particularly notable gaps, however. First, China and the United States have not agreed to exchange any launch notifications.⁴ Second, as indicated in table 1, the range thresholds that trigger notification requirements are generally quite long. Yet tests of shorter-range missiles could also spark escalation if conducted from ships or aircraft close to an adversary’s borders or from the territory of, or in the direction of, a U.S. ally. Third, no state has committed to providing notifications about tests of boost-glide missiles. Because boost-glide missiles are maneuverable, their tests are actually more likely to be misinterpreted as attacks than tests of ballistic missiles, which fly along predictable trajectories after burnout. Fourth, no state has agreed to notify others of missile defense tests, even though either the interceptor or the target missile, which could follow a ballistic or boost-glide trajectory, could be interpreted as a threatening offensive missile prior to interception (or self-destruction, should interception not occur). Fifth, there is currently no requirement on any state to provide notifications of any sub-orbital space launch—that is, a launch that places an object on a trajectory that returns to Earth, as opposed to a trajectory that takes it into Earth orbit or outer space. Yet such tests, which can be conducted for scientific research or for the development of direct-ascent anti-satellite weapons, can be misinterpreted as attacks—as the 1995 sounding rocket incident demonstrates.

Table 1: Comparison of Launch Notification Regimes
Notification Requirement	China-Russia (2009 agreement)	Russia-United States (1988 agreement)	China-United States
Minimum range of ground-launched ballistic missile	2,000 kilometers (1,200 miles)	5,500 kilometers (3,400 miles)	No notifications required
Minimum range of submarine-launched ballistic missile	2,000 kilometers	600 kilometers (370 miles)
Minimum range of air-launched ballistic missile	2,000 kilometers	No notification required
Boost-glide missile test	No	No
Missile defense test	No	No
Direction of test	Toward the other statea	Any
Post-launch notification	Yes	No
Space launch to Earth orbit or outer space	Yes	Yesb
Sub-orbital space launch	No	No
Exemption for special cases	Yes	No
aChina is required to notify Russia of launches to the west, northwest, north, and northeast. Russia is required to notify China of launches to the northeast, east, southeast, and south. b Pursuant to the Hague Code of Conduct.

Solution Concept

These deficiencies, paired with China’s increasing capability to detect missile launches, suggest that China, Russia, and the United States should share an interest in developing a more comprehensive approach to launch notifications.⁵ The proposal for a trilateral regime described below includes elements from the 1988 U.S.-Soviet and 2009 Chinese-Russian agreements, as well as from a never-implemented 2000 memorandum of understanding between Russia and the United States to enhance their notification regime. Helpfully, all these agreements contain various identical or almost identical definitions and rules (such as the instructions for describing the planned impact area of a missile test).

The following proposal aims to address all five lacunae. Notifications would be required for launches that exceed a certain minimum threshold for planned distance, apex altitude, or speed, depending on the type of launch (the risks of escalation from tests that do not meet the threshold would be small). In the case of U.S. missile defense tests, these thresholds would require Washington to report on tests of SM-3 interceptors and Ground-Based Interceptors, but not on slower systems, such as Terminal High Altitude Area Defense interceptors (of course, the thresholds would apply to all participants of the agreement equally).

Verification

A verification system would not be needed for this proposal. In fact, this proposal is valuable precisely because Russia and the United States have sophisticated capabilities to detect missile and space launches and China is rapidly acquiring them, creating the risk of a launch being detected and misinterpreted.

Assessment

Technical feasibility. This proposal should be straightforward to negotiate and implement. The one required innovation would be a mechanism for China and the United States to exchange notifications.

Political feasibility. Through their participation in existing launch notification regimes, China, Russia, and the United States have all recognized the risks of escalation as a consequence of a misinterpreted test or space launch. This proposal would benefit each state by closing a number of significant gaps in those regimes.

The political obstacles facing this proposal are relatively small—at least compared to other concepts for engaging China—since no limits would be placed on any capabilities or activities. Nonetheless, when it comes to trilateral arms control, even relatively small barriers are large in absolute terms, primarily because of the poor state of U.S.-Chinese relations.

First, both China and the United States are more concerned about deliberate aggression than they are about inadvertent escalation, increasing the difficulty of generating political traction. Yet both states have recognized the possibility that escalation may not be deliberate; for example, they both participate in the 2014 Code for Unplanned Encounters at Sea, which aims to reduce the risks associated with ships operating in proximity to one another. An even more relevant precedent was set when China announced its missile tests in advance during the 1995–1996 Taiwan Strait Crisis.⁶

Second, even if Beijing does not object to the principle of providing launch notifications to Washington, it may fear that doing so will lead to more pressure to engage in further arms control steps. Meanwhile, domestic critics in the United States may not view a launch notification regime as a meaningful step toward the goal of limiting China’s nuclear forces. Ultimately, however, decisionmakers in each state should ask themselves whether the proposed regime would, in itself, enhance their state’s security; if it would, they should support it, even if they disagree about future steps. After all, U.S. participation would not reduce Washington’s leverage to push for further steps, and Chinese participation would not reduce Beijing’s ability to resist them.

Finally, there may be concern that notifications could cue additional espionage activities, such as pre-positioning intelligence assets, to monitor launches. This concern is likely to be most acute in Beijing because of its distrust of the United States and because it can currently avoid notification requirements, pursuant to its agreement with Russia, by launching away from Russia or by invoking an exemption permitted in “special cases.”⁷ However, even Moscow and Washington may have concerns about the increase in transparency compared to their existing bilateral regime.

That said, the warning afforded by launch notifications would not significantly enhance the effectiveness of intelligence-collection activities. China, Russia, and the United States already have, or are acquiring, early-warning satellites, which can continuously monitor launches. Similarly, visual reconnaissance satellites are likely to observe test preparations, even though the coverage they provide is episodic. Participants could try to take advantage of a launch notification by pre-positioning ships or aircraft. However, for safety reasons, tests over the ocean are generally preceded by safety warnings already. Meanwhile, aircraft are unlikely to be able to get close enough to monitor a test over land without violating other countries’ airspace.

Notes

¹ Peter Vincent Pry, War Scare: Russia and America on the Nuclear Brink (Westport, CT: Praeger, 1999), 214–227.

² Robert Jervis, Perception and Misperception in International Politics, new edition (Princeton, NJ: Princeton University Press, 2017), xxx-xxxviii, 143–172, 203–216.

³ “China, Russia Extend Notification Agreement for Ballistic Missile, Carrier Rocket Launches,” Xinhua, December 15, 2020, http://www.xinhuanet.com/english/2020-12/15/c_139591997.htm.

⁴ In practice, safety warnings can act as de facto launch notifications. However, because China tests over land, it has no need to warn mariners and is inconsistent about warning aviators.

⁵ For a five-state proposal, see Frank O’Donnell, “Managing Nuclear Multipolarity: A Multilateral Missile Test Pre-Notification Agreement,” Washington Quarterly 43, no. 3 (2020): 177–196.

⁶ For example, “China Announces Missile Launch Training,” United Press International, July 18, 1995, https://www.upi.com/Archives/1995/07/18/China-announces-missile-launch-training/5045806040000.

⁷ Agreement Between the Government of the Russian Federation and the Government of the People’s Republic of China on Notifications of Launches of Ballistic Missiles and Space Launch Vehicles, 2010, Section 2.5.

Military communication and early-warning satellites in high-altitude orbits play critical roles in enabling nuclear operations—so much so, in fact, that they might be attacked as a prelude to a nuclear strike. However, threats to space-based nuclear C3I capabilities could also arise unintentionally. States periodically reposition their satellites to optimize their performance. If repositioning brought a satellite into proximity with one involved in nuclear operations, it could be misconstrued as preparation for an attack against the latter—especially in a crisis or conflict. To make matters worse, many—perhaps all—satellites involved in nuclear operations are dual-use. As a result, in a conventional conflict, they might be attacked in an attempt to disrupt nonnuclear operations being conducted by their possessor. Such attacks, however, would have the effect of degrading the target state’s nuclear C3I system.

Inadvertent threats to, and attacks on, space-based nuclear C3I capabilities would not be preparations for a nuclear war, but they could risk being interpreted as such—potentially sparking catastrophic escalation.¹ In fact, the United States has threatened to resort to nuclear use should its nuclear C3I system come under attack.² China and Russia are probably less reliant on satellites than the United States for nuclear C3I. Even so, attacks by the United States, or even perceived preparations for them, against any Chinese or Russian satellites involved in nuclear operations would still be very provocative—especially if the target were Russia’s early-warning satellites, given its launch-under-attack posture.³

The American and Russian nuclear C3I systems, and perhaps the Chinese system too, use satellites in two different kinds of high-altitude orbits: geostationary and Molniya. Geostationary satellites remain above a fixed point on the Earth’s equator at an altitude of roughly 36,000 kilometers (22,000 miles). The United States uses this orbit for communication satellites involved in nuclear operations (all of which are dual-use).⁴ An object in a Molniya orbit (a type of highly elliptical orbit) hangs above the Northern Hemisphere at altitudes approaching 40,000 kilometers (25,000 miles) before it quickly traverses the Southern Hemisphere at much lower altitudes. Russia’s early-warning satellites are located in such orbits.⁵ Its Unified Satellite Communication System (which is likely used for both nuclear and conventional operations) and the United States’ space-based early-warning system (which is definitely dual-use) comprise satellites in both geostationary and Molniya orbits.⁶ Less is known about the Chinese nuclear C3I system. Various Chinese military communication satellites and at least one possible early-warning satellite operate in geostationary orbit—though it is not known for sure whether any are involved in nuclear operations.⁷

Inadvertent threats to, and attacks on, space-based nuclear C3I capabilities would not be preparations for a nuclear war, but they could risk being interpreted as such—potentially sparking catastrophic escalation.

To varying degrees, China, Russia, and the United States have developed, tested, and deployed weapons that are designed, or could be used, to attack satellites.⁸ The difficulty of attacking satellites increases with altitude. As a result, two of the technologies that pose acute threats to satellites in low-altitude orbits would likely be much less effective against objects in geostationary or Molniya orbits. For the foreseeable future, ground-based directed-energy weapons, which focus energy on a target with, for example, a laser, will simply not be powerful enough to threaten satellites at high altitudes by damaging their sensors or other components.⁹ Ground-based direct-ascent missiles designed to destroy satellites kinetically could prove somewhat more effective, but because their launches could be detected by a state with space-based early-warning sensors and they require hours to reach high altitudes, potential targets might have time to maneuver and thus evade an incoming interceptor.

In contrast to ground-based weapons, space-based weapons present a significant threat against high-altitude satellites today. So-called co-orbital weapons (sometimes called space mines) would be launched well in advance of any attack and dwell in an orbit that would enable them to reach potential targets relatively quickly. If activated by their possessor, they could then attack other satellites—either by colliding with them or by using a kinetic or nonkinetic standoff weapon. Such attacks could occur more quickly and would be more difficult to detect than operations involving ground-based direct-ascent weapons. Many objects could be used as co-orbital weapons, including some satellites that were not designed for that purpose.¹⁰ 

No destructive anti-satellite testing has been undertaken against satellites in high-altitude orbits. However, in the last decade, a number of geostationary satellites have been closely approached by others—including by Chinese, Russian, and U.S. satellites.¹¹ These operations may have been explicit demonstrations or tests of an anti-satellite capability, but even if they were not, they demonstrate that such a capability is an inherent consequence of a satellite’s possessing a high degree of orbital maneuverability. The U.S. Defense Intelligence Agency assesses, for example, that “China is developing sophisticated on-orbit capabilities, such as satellite inspection and repair, at least some of which could also function as a weapon.”¹²

Reducing the threat posed by co-orbital weapons to satellites in geostationary and Molniya orbits would mitigate the danger of inadvertent nuclear escalation. Unfortunately, efforts to establish effective arms control in space—or even to build consensus on what constitutes unacceptable behavior—have largely stalled in multilateral fora.¹³ A trilateral approach focused on high-altitude orbits may be a fruitful way forward. It would bypass the complexities of multilateral diplomacy and focus on preventing the serious and shared danger of nuclear war.

Solution Concept

Establishing keep-out zones around high-altitude satellites could help reduce the vulnerability of key nuclear C3I capabilities. Specifically, China, Russia, and the United States should commit not to maneuver their satellites within an agreed minimum distance—700 kilometers (430 miles) in any direction—of another participant’s high-altitude satellites (with the exception of repositioning maneuvers conducted one at a time and declared in advance). This agreement would apply only to satellites nationally owned by China, Russia, and the United States and not to privately owned satellites or to satellites owned by other states (so would not contravene the 1967 Outer Space Treaty’s prohibition on “national appropriation”).

Currently, the regulation of high-altitude satellite orbits is minimal. The International Telecommunication Union (ITU), a United Nations agency, allocates slots to geostationary broadcast and communication satellites in order to prevent interference—though these slots can overlap if satellites operate on different frequencies or broadcast to non-contiguous regions on the ground. Participation in the ITU is voluntary and is designed only to minimize broadcast interference.

Establishing keep-out zones would go further than the ITU rules by applying to all Chinese, Russian, and U.S. satellites in both geostationary and Molniya orbits—not just geostationary satellites broadcasting at a particular frequency band—without permitting any overlap. It would begin to establish rules of the road for good behavior in space and help break the deadlock in improving space governance. Even recognizing that keep-out zones could not physically prevent one participant state from attacking another’s satellites in conflict—although the proposed agreement would still apply then—they would still help to reduce escalation risks in three ways.

First, keep-out zones would mitigate the danger that repositioning operations could lead one state to wrongly conclude that one or more of its satellites were under attack—that is, the zones would help to define the difference between innocuous and aggressive actions in space. Even (or perhaps especially) in a conflict, a state that did not intend to attack a nuclear C3I satellite belonging to its adversary would have a clear incentive to abide by rules designed to prevent such threats from arising inadvertently.

Second, even if one participant decided to attack another’s satellites—for whatever reason—keep-out zones could buy time. An attacking satellite would typically have to close in on a target before launching an attack (how close it would need to come would depend on its capabilities).¹⁴ This process would not be instantaneous. If the target state detected a violation of its keep-out zones before the attacking satellites were able to execute the attack, it could take preventative action (by, for example, maneuvering its satellites away from the attacking ones). Increasing the warning time of an intentional attack would also reduce the likelihood of escalation resulting from time pressure.

The margin of warning afforded by keep-out zones would depend, in part, on their size. Fuel-efficient maneuvers in geostationary orbit to cross from the edge to the center of a 700-kilometer keep-out zone would require about one day (see appendix B for more details). Faster crossing would be possible by using larger amounts of fuel. For example, the same keep-out zone could be crossed in six hours by expending the same amount of fuel that a communication satellite typically uses each year for station keeping (that is, making minor adjustments so the satellite remains in its correct orbit during day-to-day operations). Larger keep-out zones would buy more warning time and further complicate attacks—but they would be more disruptive to satellite operations. The keep-out distance of 700 kilometers proposed here aims to strike a balance between increasing warning and reducing disruption.

Third, each state could use negotiations to underscore to the others the dangers of attacking its high-altitude satellites. Such messaging could reduce the likelihood of one participant’s deliberately attacking another’s dual-use satellites in an effort to win (or at least not lose) a conventional war because it had underestimated the consequent risk of nuclear escalation.

Implementing this proposal in geostationary orbit—where one satellite would essentially have to tail another to approach it—would be relatively straightforward. Two satellites in quite different Molniya orbits, however, may occasionally happen to pass close to one another, creating a complication. Because each participant is equally responsible for such a conjunction, there would be no obvious way of deciding which participant should be required to take action to avoid it. For this reason, there should be no requirement to do so, though each participant should be required to inform the other of the impending approach. In any case, conducting an attack during one of these rare conjunctions would be technically difficult since the relative velocities of the satellites involved can be very large.

To ease implementation, only declared satellites should be afforded the protection of a keep-out zone. But because all the participants’ nationally owned satellites, declared or not, must respect keep-out zones, controversary could arise about the ownership of a given satellite. States should commit to discussing such concerns at annual implementation meetings or, if urgent, through diplomatic channels.

Today, a small number of Chinese, Russian, and U.S. geostationary satellites are typically located within 700 kilometers of each other. To establish keep-out zones, some of these satellites would need repositioning—but this should not be onerous and would not meaningfully impact the participants’ capabilities. Table 2 shows the number of geostationary satellites that would need to be moved as of January 1, 2021, depending on the size of the keep-out ones. Zones with a radius of 700 kilometers (just under 1 degree) would only require seven satellites to be moved. Regardless, repositioning is a routine operation, and only minor orbital adjustments would be needed (though the participants would have to negotiate, on the basis of reciprocity, who would move which satellites).

Table 2: Number of Geostationary Satellites That Would Need Repositioning to Implement Keep-Out Zones
Separation (degrees)	United States–Russia	Russia-China	China–United States	Total
0.5	2	1	2	5
1.0	3	1	3	7
1.5	7	1	5	13
2.0	7	2	6	15
Source: Author calculations based on satellite data as of January 1, 2021, courtesy of Union of Concerned Scientists, “UCS Satellite Database,” January 1, 2021, https://www.ucsusa.org/resources/satellite-database.

Verification

Participants would verify compliance with this proposal by using their space situational awareness capabilities to periodically measure the positions of satellites in geostationary and Molniya orbits. This data—longitude, latitude, and altitude—enables not only the distance between satellites to be computed but also whether one satellite is drifting in the direction of another. A state would likely want to monitor its own satellites and those belonging to other participants. Failing to detect another participant’s satellite at its expected location would be evidence that it was maneuvering and could cue a search.

Participants would presumably want to be able to observe satellites in geostationary and Molniya orbits frequently enough that, in the time between observations, a co-orbital weapon could move only, say, one-half or one-third of the distance from the edge of a keep-out zone to the satellite at its center. There can be no definitive estimate of this time period since it would depend on how much fuel is available to the attacking satellite and, of that, how much the attacker would be willing to expend. Nonetheless, ideally, each participant would probably want to image any satellites near its own every two or three hours.

There are various means to detect the positions of satellites in high-altitude orbits.¹⁶ In each case, multiple sensors are required to monitor all relevant satellites. For ground-based systems, these sensors must be spread around the Earth.

• Ground-based optical sensors—telescopes—can detect satellites by observing reflected light from the sun or from a laser used to illuminate the target. They are the simplest, most inexpensive, and most readily available means to detect satellites, though they suffer from various limitations. Most notably, they cannot operate in daylight or when skies are overcast. However, commercially available infrared telescopes have proven capable of tracking geostationary satellites during the day, thus addressing a key weakness of existing optical telescopes.¹⁷
• Space-based optical sensors are capable of high-cadence imaging of other satellites, though they are considerably more expensive than ground-based telescopes. Their performance depends on the number of available sensors and their orbits.
• Ground-based radio telescopes can be used to locate satellites by intercepting their communications. Such observations are not affected by weather or time of day but are only possible when a satellite is transmitting.
• Some ground-based radars are capable of detecting and imaging high-altitude satellites. They are not affected by weather or time of day, but they are expensive and have a particularly limited field of view. They are therefore poorly suited to wide-area searches, but they can accurately measure the position of satellites whose approximate locations are known.

China, Russia, and the United States have long had an interest in developing effective space situational awareness capabilities. These capabilities are shrouded in opacity, particularly in the cases of China and Russia—though some significant inequalities are apparent. (Appendix C summarizes what is publicly known about each state’s capabilities.) For its part, the United States is likely already capable of verifying the proposed agreement—at least for most of geostationary orbit (it may lack radar coverage over parts of the Eastern Hemisphere). The opacity of Russian and Chinese capabilities makes it difficult to determine whether they could also verify the agreement. Russia has a fairly extensive space situational awareness system, though it likely has less capability than the United States. Chinese capabilities, meanwhile, are more opaque still and likely less sophisticated than Russia’s.

Feasibility

Technical feasibility. The primary technical challenge to verification is uncertainty about the adequacy of existing space situational awareness capabilities—China’s and Russia’s, in particular. (Making minor adjustments to the positions of a small number of satellites to establish keep-out zones should be straightforward, though deciding who would move which satellite could become somewhat contentious.)

Even if not all the participants have adequate verification capabilities today, however, they are likely on a trajectory to acquire them. Accurately tracking the location of highly valuable satellites—and potential threats to them—is clearly in the national interests of China, Russia, and the United States, regardless of whether they try to mitigate those threats cooperatively. Moreover, acquiring effective space situational awareness capabilities is critical to the development of anti-satellite weapons, which all three states appear to want. At the same time, cheaper ways of monitoring high-altitude satellites, such as infrared telescopes, are emerging. Any participants currently lacking the required verification capabilities might still be able to detect noncompliance, albeit without high confidence.

Political feasibility. One key political challenge is that China and Russia appear to want the ability to hold U.S. satellites in high-altitude orbits at risk, while the United States may desire a similar capability against China and Russia. These incentives are probably asymmetric right now as the U.S. military relies more heavily on satellites, which could present tempting targets for China and Russia during a conflict.

But the incentives may be evening out. China and Russia are investing heavily in military satellites, including in high-altitude orbits. Notably, Russia is rebuilding its space-based early-warning system and has offered assistance to China, which is developing one for the first time.¹⁸ Russia relies on a launch-under-attack policy to help ensure the survivability of its nuclear forces, while China appears to be moving in the same direction. While both states also have a network of ground-based early-warning radars, they should seek (as the United States does) to have confirmation of an incoming attack from two physically independent detection systems before deciding to launch their nuclear forces.

Furthermore, while attacks on high-altitude satellites could provide military benefits, they could also create serious risks. In fact, because they could undermine nuclear C3I capabilities, they would be even more escalatory than attacks on satellites orbiting at lower altitudes (which would hardly be risk-free). As a result, an agreement that focuses narrowly on enhancing the survivability of satellites in geostationary and Molniya orbits—and thus reduces the shared risk of nuclear war—may be of interest to Beijing, Moscow, and Washington.

Notes

¹ Acton, “Escalation Through Entanglement.”

² U.S. Department of Defense, “Nuclear Posture Review,” 21.

³ Arbatov, Dvorkin, and Topychkanov, “Entanglement as a New Security Threat,” 38–39.

⁴ “Advanced Extremely High Frequency System,” Air Force Space Command, March 22, 2017, http://www.afspc.af.mil/About-Us/Fact-Sheets/Display/Article/249024/advanced-extremely-high-frequency-system/.

⁵ Future satellites may be placed in geostationary orbit. Pavel Podvig, “Fourth Tundra Early-Warning Satellite Is in Orbit,” Russian Forces (blog), May 22, 2020, http://russianforces.org/blog/2020/05/fourth_tundra_early-warning_sa.shtml.

⁶ V.A. Grigoryev and I.A. Khvorov, “Military Satellite Communications Systems: Current State and Development Prospects,” Military Thought 16, nos. 3–4 (July 1, 2007): 149–150; Jana Honkova, “The Russian Federation’s Approach to Military Space and Its Military Space Capabilities,” George C. Marshall Institute, November 2013, 26–28; and Office of the Secretary of Defense, “Report to the Defense and Intelligence Committees of the Congress of the United States on the Status of the Space Based Infrared System Program,” U.S. Department of Defense, March 2005, 3, http://nsarchive.gwu.edu/NSAEBB/NSAEBB235/42.pdf.

⁷ Stephen Clark, “China Launches Military Satellite Toward Geostationary Orbit,” Spaceflight Now, February 7, 2021, https://spaceflightnow.com/2021/02/07/china-launches-military-satellite-toward-geostationary-orbit/.

⁸ Brian Weeden and Victoria Samson, eds., “Global Counterspace Capabilities: An Open Source Assessment,” Secure World Foundation, April 2021, xiv–xxiii, https://swfound.org/media/207162/swf_global_counterspace_capabilities_2021.pdf.

⁹ Satellites in Molniya orbits spend a portion of their orbit at low altitudes near the South Pole where they may be vulnerable to direct ascent and directed-energy weapons—though their high speeds during this part of their trajectory helps mitigate this vulnerability.

¹⁰ David Wright, Laura Grego, and Lisbeth Gronlund, “The Physics of Space Security: A Reference Manual,” American Academy of Arts and Sciences, 2005, 136, https://www.ucsusa.org/sites/default/files/2019-09/physics-space-security.pdf.

¹¹ Weeden and Samson, eds., “Global Counterspace Capabilities,” 1-7–1-11, 2-10–2-13, 3-6 –3-10.

¹² Defense Intelligence Agency, “Challenges to Security in Space,” [February 2019], 21, https://apps.dtic.mil/sti/pdfs/AD1082341.pdf.

¹³ Michael J. Listner, “The International Code of Conduct: Comments on Changes in the Latest Draft and Post-Mortem Thoughts,” Space Review, October 26, 2015, https://www.thespacereview.com/article/2851/1.

¹⁴ Some co-orbital weapons may need to physically rendezvous with a target to damage it. Others may be armed with standoff munitions weapons that could attack a target from a distance. However, maneuvering to allow the use of a standoff munition with a relatively short range, say 50 kilometers (31 miles), would not require significantly less time than manuevering to reach the satellite itself. Long-range standoff weapons would be more technically difficult to develop and deploy.

¹⁵ Maintaining such a minimum distance is possible because repositioning maneuvers involve a change in altitude. A minimum distance of 250 kilometers corresponds to a slow drift rate of about 1 degree per day. Faster repositioning maneuvers would increase the distance of closest approach.

¹⁶ George Veis, “Optical Tracking of Artificial Satellites,” Space Science Reviews 2, no. 2 (August 1, 1963): 250–296; Grant H. Stokes et al., “The Space-Based Visible Program,” Lincoln Laboratory Journal 11, no. 2 (1998): 207–236; Chuck Livingstone, “Radar Systems for Monitoring Objects in Geosynchronous Orbit,” Technical Report TR 2013-009, Defence Research and Development Canada, June 2013, https://cradpdf.drdc-rddc.gc.ca/PDFS/unc125/p537646_A1b.pdf.

¹⁷ Jeffrey Shaddix et al. “Daytime GEO Tracking With ‘Aquila’: Approach and Results From a New Ground-Based SWIR Small Telescope System,” 2019 Advanced Maui Optical and Space Surveillance Technologies Conference, Maui, Hawaii, September 17–20, 2019.

¹⁸ Christopher Weidacher Hsiung, “Missile Defense and Early Warning Missile Attack System Cooperation: Enhancing the Sino-Russian Defense Partnership,” IFS Insights, Norwegian Institute for Defense Studies, January 1, 2020, https://www.jstor.org/stable/resrep25799?seq=1#metadata_info_tab_contents.

Over the past few years, the United States has restarted its efforts to develop space-based missile defenses. In 2018, the U.S. Congress directed the Department of Defense to identify potential technologies for, and to estimate the costs of, deploying a space-based missile defense layer.¹ Research into space-based defenses was funded throughout the remainder of the Trump administration.² Given their absence from the Biden administration’s Fiscal Year 2021 budget request, their short-term future is less clear—although, over the long term, the United States is likely to remain interested in them, while China and Russia are likely to remain concerned about them.

Space-based missile defenses—involving kinetic interceptors or nonkinetic technologies, such as directed-energy weapons—are capable, at least in theory, of addressing some of the weaknesses of terrestrial missile defense systems. For example, the United States’ Ground-based Midcourse Defense system is vulnerable to decoys deployed in the vacuum of space or to hypersonic gliders that fly below the interceptors’ engagement altitude. Space-based defenses could overcome such countermeasures by engaging a missile in its boost phase, while its engines are still operating and before decoys can be deployed or a glider released. Alternatively, space-based defenses could be configured to intercept ballistic missiles during their midcourse phase when they are unpowered. In particular, directed-energy weapons offer the potential to engage large numbers of incoming warheads (and decoys).

Chinese and Russian officials have repeatedly expressed concerns over existing and possible future U.S. ballistic missile defenses. Russia’s developmental exotic weapons are intended to circumvent them. Because some of these weapons—the Burevestnik cruise missile and Poseidon torpedo, in particular—could evade space-based interceptors, concerns that the United States may develop and deploy space-based defenses could make Russia less amenable to limits on its exotic systems. U.S. officials, meanwhile, have claimed that China is “looking at” nuclear-powered cruise missiles and torpedoes, perhaps because many of its existing programs to combat U.S. missile defenses—including arming missiles with multiple warheads and developing an intercontinental hypersonic glider—could theoretically be vulnerable to space-based defenses.³

Space-based missile defenses present daunting technical challenges and are likely to be extraordinarily expensive.

These concerns may also lead China and Russia to deploy anti-satellite weapons in even larger numbers than currently planned to ensure that they are able to target the satellites on which interceptors would be based or the sensors that would enable them. Such deployments, even if undertaken solely to combat missile defenses, would increase the threat to all U.