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But China’s sometimes vague misgivings about U.S. missile defense are not the only source of ambiguity fueling the two countries’ dispute. Given Chinese concerns about the motivations behind U.S. missile defense programs, it is worthwhile to examine Washington’s objectives more closely.

U.S. missile defense policy has maintained a lot of continuity over the last few decades.1 Various U.S. administrations have sought to protect the United States and its allies from missile threats emanating from so-called rogue states, while also trying to assure Russia and China about U.S. strategic intentions. The U.S. government’s 2019 Missile Defense Review (MDR) report repeats the long-standing policy that U.S. homeland missile defense is intended to “protect against possible missile attacks on the homeland posed by the long-range missile arsenals of rogue states, defined today as North Korea and Iran.”2 In the event of a conflict, the MDR report states that the United States would seek to “defend, to the extent feasible, against a ballistic missile attack upon the U.S. homeland from any source.” But the document also implies that U.S. homeland missile defense systems are not scaled to deal with Chinese or Russian strategic missile attacks. According to the report, the “United States relies on nuclear deterrence [emphasis added] to address the large and more sophisticated Russian and Chinese intercontinental ballistic missile capabilities.”

But Beijing remains uneasy about certain ambiguities in the U.S. stance on missile defense. China is concerned that the United States, citing the evolving nature of potential “rogue missile threats,” has continued to reject “any limitation or constraint on the development or deployment of missile defense capabilities needed to protect the homeland.”3 From a Chinese perspective, key elements of U.S. capabilities, policies, and future plans for missile defense create serious ambiguities regarding the objectives of its programs. This lack of clarity is one of the most important sources of China’s deep distrust of U.S. intentions, and this ambiguity leads Beijing to suspect that, in reality, Washington’s objectives are more ambitious than its proclaimed goals. Specifically, U.S. capabilities and policies give rise to five main elements of ambiguity that contribute to the perception gap between Beijing and Washington.

Is U.S. Strategic Missile Defense Aimed at China?

China remains genuinely skeptical that U.S. missile defense systems are not ultimately intended to undermine its nuclear deterrent. Repeated U.S. claims to the contrary, including in the 2010 MDR report and the 2019 MDR report, have done little to dispel those fears.4 Trump’s speech at the rollout of the 2019 MDR report—which most Chinese experts believe was prepared ahead of time and not given off the cuff—suggested that the United States may have a more ambitious unstated missile defense policy than the one set out in the report.5 He claimed, for example, that the U.S. military seeks “to ensure that we can detect and destroy any missile launched against the United States—anywhere, anytime, anyplace.”

Inconsistencies among U.S. official statements do not reassure Beijing but instead heighten Chinese concerns that the MDR report set out a politically correct version of a secretive and more ambitious U.S. missile defense policy. Comments from U.S. lawmakers and experts calling for the United States to defend its homeland against large-scale Russian and Chinese missile strikes add to Beijing’s suspicions.6 In light of such comments, some Chinese experts believed, even before the 2019 MDR report was released, that the United States might officially seek to undermine China’s and Russia’s nuclear deterrents.7 Chinese analysts now believe that this objective was absent from the MDR report not because the U.S. government does not harbor this objective but because it lacks an internal consensus. Consequently, they suspect that there is still serious interest in U.S. policy circles in moving in that direction.

Many Chinese strategists suspect that the costs and difficulties of such an endeavor are the main roadblock. They assume the United States has not yet sought to develop strategic missile defense systems against Russia or China not because Washington does not want to but because it cannot afford to—due to the prohibitively high economic costs and formidable technological challenges.8 For example, the administration of former president Barack Obama, which was relatively moderate on missile defense, stated in the 2010 MDR report that the U.S. homeland missile defense system “does not have the capacity to cope with large scale Russian or Chinese missile attacks.”9

Chinese experts take such statements as a U.S. acknowledgment of the (undesirable) reality that its existing capabilities are insufficient, not evidence of limited U.S. intentions. They suspect that U.S. homeland missile defense systems are focused on the more manageable task of countering North Korean and Iranian long-range missiles only because the United States is more confident it can handle these rogue states’ relatively few and less sophisticated missiles. Hardly any Chinese experts seem to doubt that, if the United States felt it could acquire effective strategic defenses against China, it would do so.

If the U.S.-China strategic rivalry continues to grow, Beijing worries Washington might become increasingly motivated to seek such a capability. As Wu Riqiang predicts, “the U.S. development of missile defense probably seeks to achieve two goals: it would first use North Korea as the excuse to quietly develop missile defense technologies and integrate different systems; after the technologies become mature it would then enlarge the scope of deployment to neutralize the Chinese and even the Russian nuclear retaliation capabilities.”10 More and more Chinese experts may embrace this view, as they have become convinced that the United States seeks to maintain hegemony by comprehensively trying to suppress and contain China.11

The open-ended nature of the most ambitious U.S. missile defense programs in development does little to defuse this ambiguity over long-term U.S. strategic intentions12 The renewed interest in the 2019 MDR report in space-based interceptors is a case in point. The potentially huge scale and expense of this U.S. program leads Chinese military experts to see it as part of the “U.S. big power competition strategy,”14 not as an attempt to counter the limited threats that rogue states pose.

The open-ended nature of the most ambitious U.S. missile defense programs in development does little to defuse this ambiguity over long-term U.S. strategic intentions.

Chinese strategists also worry that U.S. defense planners may seek to use missile defense to keep foes from wielding emerging military technologies like hypersonic missiles. The MDR report also outlined the goal of developing “defensive architectures to defeat hypersonic threats,”14 without stating which types of hypersonic threats the United States intends to counteract. Although some countries are developing regional-range hypersonic weapons probably for conventional strikes, longer-range hypersonic systems will have some role to play in delivering nuclear warheads over intercontinental distances, including Russia’s Avangard boost-glide system.

Beijing worries that U.S. homeland missile defense may aim to foil any possible Chinese pursuit of hypersonic missiles to bolster its nuclear second-strike capability. Chinese experts have claimed that the most important benefit of hypersonic weapons is the unique ways they can penetrate ballistic missile defense systems—an indication that China may plan to eventually develop intercontinental, nuclear-armed hypersonic systems.15 Given that the United States has not clarified its long-term goals for defending against hypersonic weapons, Beijing may suspect that Washington aims to deny China this option.

More importantly, more advanced U.S. strategic missile defense of this kind would not merely threaten the hypersonic missiles China may seek to wield someday. Because hypersonic weapons are generally believed to be more technically challenging to intercept than ballistic missiles, China may worry that a U.S. missile defense system capable of intercepting intercontinental-range hypersonic missiles would pose a greater threat to regular Chinese ICBMs than traditional U.S. missile defense systems.

But what it would take to intercept hypersonic weapons may be more complex than is generally understood. Nuclear expert James Acton, for example, has argued that intercepting boost-glide weapons—an important type of hypersonic weapons—in their terminal phase of flight, which would enable “point defense” of relatively small geographic areas, may be technically feasible. By contrast, seeking to protect a much wider swath of territory with “area defenses” would require intercepting incoming missiles during mid-course flight—a much more formidable task.16

A U.S. point defense strategy may prove less destabilizing, but some Chinese experts may not fully grasp the difference. If the U.S. military embraces this view and focuses on developing and deploying point defenses to protect a few key military and political targets against hypersonic weapons, the threat to Beijing’s strategic nuclear deterrent should be limited. In that case, China would still be able to retaliate against many unprotected population centers and industrial targets across the U.S. homeland. But most Chinese policy experts appear to be unaware of such technical distinctions, and they may read the U.S. plan to defend against hypersonic missiles as an ambitious declaration of Washington’s intent to try to eliminate all future long-range missile threats to the U.S. homeland. Moreover, the United States’ interest in being able to track missiles at every stage of their flight combined with its exploration of space-based interceptors make Chinese experts worry that Washington is vigorously seeking boost-phase intercept capabilities—an approach that could simultaneously undermine both ICBMs and boost-glide vehicles.17

Could U.S. Strategic Missile Defense Aimed at North Korea Be Used to Target China?

Another lingering question is whether U.S. strategic missile defense is designed chiefly or solely to counter the arsenals of rogue states like North Korea or those of major powers like China. Chinese experts point to the United States’ rejection of limits on its missile defense programs as evidence that its true goals are more ambitious than warding off Iranian and North Korean long-range missiles.18 Chinese analysts generally assume that the United States could take measures to make its missile defense capabilities less threatening to China, but that it has chosen not to do so.

But this is not wholly a question of U.S. intentions. It could be very technically challenging, if not impossible, for the United States to build a homeland missile defense system of a scope and scale that could defend against North Korean long-range missiles but not threaten China’s nuclear deterrent. The ambiguities imposed by such structural constraints are an important source of the U.S.-China perception gap.

It could be very technically challenging . . . for the United States to build a homeland missile defense system . . . that could defend against North Korean long-range missiles but not threaten China’s nuclear deterrent.

The United States deploys forty-four ground-based interceptors (GBI) in Alaska and California.19 The U.S. military appears to work from the assumption that four interceptors would need to be fired at each incoming ICBM to try to increase the probability of a successful intercept.20 This number indicates that, today, the United States may be able to intercept eleven North Korean ICBMs, a figure that is similar to the estimated size of North Korea’s current ICBM stockpile.21 In other words, the United States appears to premise the posture of its missile defense systems on the assumption that North Korea might fire all of its ICBMs prior to any U.S. attempt to destroy them preemptively. U.S. plans to field more GBIs as the North Korean stockpile gets larger underscore this impression.22

This arsenal of U.S. interceptors could pose a similar threat to China’s larger ICBM force if a U.S. first strike markedly reduced their numbers. U.S. experts Hans Kristensen and Matt Korda estimate that, as of 2019, China has about sixty-eight launchers for three types of ICBMs that can reach the U.S. homeland—the DF-5, DF-31A, and DF-31AG.23 The introduction of the new DF-41 ICBM, likely in the near future, may add to this number, but it would not dramatically change the equation. But those numbers notwithstanding, if China were to absorb a U.S. first strike, the size of its surviving ICBM force could be very similar to—if not smaller than—North Korea’s ICBM stockpile. As a result, the same homeland missile defense capabilities that the United States deems adequate to deal with a North Korean first strike are likely to appear to Beijing as capable of undermining its second-strike capabilities if Washington were to launch a disarming first strike.

The geographical proximity of China and North Korea heightens this ambiguity. North Korean and Chinese ICBMs headed toward the United States would fly along similar trajectories, so missile defense systems positioned to deal with the former may also be able to intercept the latter. Indeed, Wu has concluded that “all missile defense systems that aim to counter North Korea would have the capabilities to counter Chinese strategic missiles.”24

Some U.S. experts and officials have tried to assuage Chinese concerns by arguing that China deploys much more advanced evasive countermeasures on its ICBMs than North Korea does. For example, Lieutenant General Ronald Kadish, then director of the Ballistic Missile Defense Organization, implied in 2000 that U.S. missile defense systems could defeat the basic countermeasures used by North Korea and other states then believed to be pursuing a rudimentary ICBM capability. But he went on to suggest that U.S. missile defense could not thwart the more sophisticated countermeasures employed by Russia or China, so neither Moscow nor Beijing (he said) had reason to worry about the survivability of their strategic deterrents.25

But that could easily change as North Korea’s arsenal matures. The rapid development of North Korea’s ICBM program suggests that Pyongyang is likely to invest heavily in advanced countermeasures.26 Moreover, some U.S. experts worry that even if North Korea could not independently develop its own advanced countermeasures, it might be able to purchase or steal them from other more advanced powers with more sophisticated missile programs.27 As a result, U.S. missile defense planners may still have strong incentives to design their defense systems to deal with advanced countermeasures, potentially undermining U.S. attempts to assure China about its second-strike capability.

One potentially less threatening alternative that U.S. experts have proposed would be for the United States to use boost-phase missile defense systems with short interception ranges to counter ICBMs launched from small countries, such as North Korea, without endangering Chinese or Russian ICBMs that are usually deployed hundreds of kilometers inland from their borders. Such systems could be surface-based, aircraft-based, or drone-based.28 The 2019 MDR report, for example, seeks to explore the option of mounting a boost-phase interceptor on F-35 aircraft. Proposed air-based, boost-phase defense systems usually have interception ranges of around 700–900 kilometers against ICBMs with burn times longer than 250 seconds, if timely and adequate cueing data on the targets is available.29 If deployed near North Korea, such systems would indeed pose very little threat to China’s ICBM forces.

But these shorter-range missile defense systems could pose other complications to China’s second-strike capabilities. For instance, such systems could be threatening to Chinese SLBMs, especially if China’s nuclear-armed submarines (SSBNs) are deployed within designated bastions in Chinese coastal waters.30 In fact, such missile defenses could even be threatening if China’s SSBNs are deployed in the open ocean. Because Chinese SSBNs seem to be relatively noisy,31 the United States may be able to detect and track them or at least identify their general operation area, giving Washington the option of deploying air-based defense systems to attempt to intercept Chinese SLBM launches during a crisis. These complications underscore that even if the United States wanted to build missile defenses against North Korea that were distinguishable from those necessary for combating China (and there is so far little evidence that it has such a desire), doing so could be very challenging, if not entirely impossible.

To compound the problem further, Chinese and U.S. experts tend to have different assessments of North Korea’s nuclear and missile capabilities. Especially when it comes to North Korea’s ICBM program, which directly threatens the U.S. homeland, U.S. experts tend to treat the threat very seriously even if North Korean technologies are not 100 percent proven.32 In comparison, Chinese experts often set a higher bar for judging whether North Korea’s capabilities constitute a realistic threat. For instance, Chinese experts have indicated that North Korea seems to still be further away from achieving a realistic ICBM threat than the United States perceives until Pyongyang masters a reliable reentry vehicle, one of the most difficult parts of an ICBM program.33 Such divergent views of how imminently North Korea will become a nuclear threat to the United States also contribute to Beijing and Washington’s disagreement over how justifiable the U.S. strategic missile defense program is.

Does U.S. Theater Missile Defense Have Strategic Implications?

On paper, U.S. policy tacitly distinguishes between the purposes of strategic and theater missile defense, but that line may be more blurred than policy documents acknowledge. The 2019 MDR report proclaims the goal of building “robust regional missile defense for U.S. forces abroad, allies, and partners against all potential adversaries,” thus emphasizing that all Chinese theater missiles are legitimate targets. Yet the document also implies that theater defense systems are not intended to defend against Chinese strategic missiles as the “United States relies on nuclear deterrence” to counter the Chinese ICBM threat.34

In practice, however, certain ambiguities between theater and strategic missile defense make it harder than such policies acknowledge to differentiate the two. This problem is not a new one. The United States and Russia tried repeatedly during the tenure of former president Bill Clinton to build a common understanding for distinguishing theater and national missile defense systems. They reached some initial agreement over theater-level interceptors with low burnout speeds (below 3 kilometers/second). Such low burnout speeds render interceptors unable to strike longer-range, faster-moving targets. But the two sides ultimately could not agree on the impact of so-called upper-tier theater missile defense systems (with burnout speeds of between 3 kilometers/second and 7 kilometers/second) on strategic missiles.35 This attempt to demarcate the distinction was abandoned in the early 2000s, and the U.S. government continued developing and deploying theater missile defense systems in East Asia and elsewhere.

On paper, U.S. policy tacitly distinguishes between the purposes of strategic and theater missile defense, but that line may be more blurred than policy documents acknowledge.

Yet, from a Chinese perspective, even interceptors with low burnout speeds can have strategic implications. If such interceptors are targeted at ICBMs in their final phase of flight, then they can be used effectively for point defense. If enough are deployed, then large areas can be defended.36 For example, Chinese experts from the China Academy of Engineering Physics—the organization responsible for building and maintaining China’s nuclear weapons—concluded that a THAAD-like theater interceptor would be approximately as effective against a theater missile as it would be against an ICBM in their respective terminal phases of flight, even without highly accurate cueing information.37

In a similar vein, a study by U.S. experts concluded that, to make a theater system truly incapable of intercepting strategic targets, the burnout speed of its interceptors would have to be significantly below 2.6 kilometers/second.38 Yet current U.S. theater interceptors have much higher burnout speeds. SM-3 Block IIA interceptors, for example, reportedly have a burnout speed of around 5 kilometers/second.39 The United States may be able to protect its entire homeland with an affordable number of such high-speed theater interceptors, especially if they are deployed on ships and can be relocated close to the U.S. homeland during crises.

These inherent technical ambiguities make the gap between theater and strategic missile defense even more narrow. This is especially true as the United States enhances its sensor network so that it can provide more timely and accurate cueing data for missile interceptors. The earlier an interceptor can be launched, the further it can fly before interception and the larger the area it can defend—an area known as its footprint.40 Better cueing data and an earlier launch of a theater interceptor can make up for its relatively slow speed and make its performance closer to that of a strategic interceptor.

It is unclear how good current U.S. sensors are at providing suitable cueing data for regional interceptors, but the United States is finetuning these capabilities and will likely be able to in the future. The legacy Defense Support Program’s early-warning satellites do not provide accurate enough tracking data to enable the launch of an interceptor. Newer Space-Based Infrared System satellites are more capable, but it is unclear whether they are good enough to generate a firing solution for an interceptor by themselves.41 Large, ground-based early-warning radars for ballistic missiles can provide extremely accurate tracking data, but their detection range is limited by the curvature of the earth, and none of them are located all that close to North Korea or Iran. But the gradual deployment of forward-based radar systems, such as the AN/TPY-2 radars in Japan and South Korea, may help to fill this gap, at least to some extent.

In addition, the United States appears set to significantly enhance its detection and tracking capabilities over time. Most importantly, there is strong domestic support in the country for building highly capable space-based sensors. The Pentagon has formulated plans to build two new discrimination radars in the Pacific. It also seeks to enhance sensor capabilities on mobile platforms, such as advanced fighter jets (including the F-35), unmanned aerial vehicles, and ships (including through the next-generation AN/SPY-6 radar). What is more, the United States is working to connect different sensor platforms to share information more efficiently. Such an integrated network would enable theater interceptors to be launched using cueing information acquired from remote sensors, thus making these interceptors potentially more effective against ICBMs.

Theater missile defense systems, in addition to their potential to intercept ICBMs directly, could also make indirect contributions to strategic missile defense. In particular, forward-deployed sensors could help resolve what U.S. experts generally regard as the biggest challenge facing mid-course interception: discriminating warheads from enemy countermeasures, including chaff and decoys.42 Chinese experts have calculated that ICBMs launched from inland China toward the United States would be visible during their initial ascent phase (immediately after the completion of the phase of powered flight) to the powerful South Korea–based AN/TPY-2 radar, which would be able to monitor the launch of warheads and countermeasures.43 As a result, these experts have concluded that this radar could assist with discrimination and be used to cue GBIs based in Alaska, making them better positioned to intercept Chinese ICBMs.

Likewise, many of the same experts believe that forward-deployed radars could be used during peacetime to monitor and gather intelligence on Chinese missile tests, including information on Chinese countermeasures. Over time, such information could help the United States better conduct warhead discrimination and thus enhance its strategic missile defense capabilities.44

These concerns are understandable, though the specific technical arguments on which they are based should be more seriously examined and debated. For instance, subsequent research suggests that the claimed capabilities of the AN/TPY-2 radar in South Korea are likely based on an incorrect understanding of the technical requirements for warhead discrimination; as a result, this radar is likely to be less effective at discrimination than some Chinese experts fear.45 Research by the U.S. Army Science Board also indicates that warhead discrimination actually requires radars to have very high sensitivity and resolution to “detect [a target’s] microdynamics.”46 There is no evidence that the AN/TPY-2 radar can do so.

In political terms, the United States’ interest in assuring China about the limits of its theater missile defense’s capabilities vis-à-vis strategic targets is also declining, after previous and repeated efforts by the Obama administration especially to assuage Russian concerns on the same issue have failed over the past decade. Obama administration officials replaced the Bush administration’s plan to set up a third site for GBI deployment in Europe with a more modest plan called the European Phased Adaptive Approach (EPAA), and they later decided to cancel phase four of the EPAA, which had envisioned the development and deployment of a more powerful SM-3 interceptor than the current U.S. plan. Unfortunately, these goodwill efforts did not blunt Russian criticism of U.S. missile defense policy and thus made some U.S. policymakers skeptical of the value of future efforts to reassure Russia or China by taking the trouble to limit U.S. theater missile defense capabilities.47

What Is the Actual Purpose of U.S. Theater Missile Defense?

The potential overlap between U.S. theater and strategic missile defense underscores the need to better understand the purpose of U.S. and allied theater missile defense. The United States explicitly seeks to defend itself and allies like Australia, Japan, and South Korea against all regional missile threats, whether nuclear or non-nuclear, including those from China. The policy of U.S. allies is more ambiguous, in terms of the intended target(s) of their missile defense. That said, the defense white papers of Japan, at least, repeatedly highlight the ability of China’s missile forces to attack Japan’s mainland and offshore islands.48

China views such theater missile defense systems as an important security threat, but this threat is ambiguous in at least two ways. First, are these defenses primarily designed to combat North Korea or do they focus more on dealing with China’s much more capable theater-level missile force? Second, in the case of countering Chinese missiles, are U.S. defense capabilities designed to intercept Chinese conventional missiles distinguishable from U.S. defense systems aiming at undermining China’s regional nuclear strike capabilities? China, presumably, may view the latter type of defenses as a greater strategic threat.

The potential overlap between U.S. theater and strategic missile defense underscores the need to better understand the purpose of U.S. and allied theater missile defense.

The geography of East Asia does not help dispel such Chinese concerns. After all, missile defense systems in Japan, South Korea, and U.S.-controlled Guam intended to intercept North Korean missiles would also be able to intercept, to some degree, incoming Chinese missiles against similar targets, depending on their exact trajectories. Base 65 of the PLA Rocket Force (formerly known as Base 51 of the Second Artillery), for example, is headquartered in Shenyang in northeastern China and commands several brigades of regional missiles reportedly located near the border with North Korea.49 If these missiles were launched against targets in Japan or South Korea, they could have trajectories similar to North Korean missiles launched against the same targets. As a result, China may be inclined to interpret current and future deployments of U.S. and allied missile defense systems targeting North Korea as actually targeting China. This tendency may become more pronounced as the U.S.-China strategic rivalry worsens.

Instead of seeking to mitigate this ambiguity, the United States may be trying to take advantage of it. Some U.S. officials and experts believe that theater missile defense systems can provide the country with diplomatic leverage over China. Specifically, senior U.S. officials have sought to use China’s concern about the THAAD deployment—by threatening to step up the deployment in South Korea—as a way to make China impose more sanctions on North Korea.50 But this strategy is likely to backfire as Beijing views it as an implicit U.S. acknowledgment of the threat its missile defense systems pose to China, reinforcing preexisting Chinese suspicions about the objectives of U.S. missile defense.

Another ambiguity concerns the level of threat that U.S. theater missile defense presents to nuclear and conventional Chinese missile forces. The United States and its allies are locked into an ongoing offense-defense competition with China in conventional military terms. And it is fair game for each player to try to shift the conventional balance in its own favor. But U.S. and allied theater missile defense systems may, in China’s view, also be intended to deny Beijing the ability to engage in nuclear retaliation against regional targets.51 Because China’s regional nuclear deterrent may, as discussed above, be more relevant than its strategic nuclear deterrent to defending its key national interests in the Asia-Pacific, Beijing may be less tolerant of the development of U.S. and allied theater missile defense systems if it sees them as more than just a conventional concern.

This ambiguity could be irresolvable. For at least two reasons, the United States and its allies cannot develop theater missile defense systems that can counter only China’s conventional theater missiles and not its regional nuclear missiles. By rough estimates, China has deployed only dozens of nuclear-capable medium- and intermediate-range ballistic missiles,52 but it has fielded more than 1,000 theater conventional missiles.53 If the United States and its allies ultimately gain the ability to defend against a large-scale Chinese strike with conventional missiles, they would also be able to intercept a much smaller wave of nuclear missiles. If China’s conventional theater missile force continues to outgrow its nuclear arsenal, this problem will become even more severe. In this sense, missile defense threatens China’s ability to employ nuclear retaliation regionally more than its capacity to employ nuclear retaliation against the U.S. homeland.

Missile defense threatens China’s ability to employ nuclear retaliation regionally more than its capacity to employ nuclear retaliation against the U.S. homeland.

Further, if Beijing’s strategy for responding to a limited nuclear attack on China or Chinese forces involves limited regional nuclear retaliation, the targets would likely be U.S. military targets, especially U.S. military bases—as opposed to purely civilian population centers in Japan or other U.S. allies—so as to limit any further escalation.54 It is generally believed, however, that China’s conventional missiles target the same U.S. military bases, as their mission is to threaten key operational and logistical nodes of the U.S. regional military network. Due to this overlap, U.S. missile defense systems capable of defending these targets from conventional missiles would have an inherent ability to defend them from nuclear attacks too.

Is U.S. Missile Defense Actually Offensive?

The troubling possibility that technological advances and research and development trends could make U.S. missile defense suitable for more offensive purposes further alarms Chinese experts. From a Chinese perspective, U.S. missile defense systems appear to be becoming increasingly offense-oriented, despite U.S. insistence that they are defensive. The potential for such defenses to enable offensive action has long been recognized—indeed, for much of the 1960s and 1970s, the United States was the main proponent of this theory.55 Essentially, a state that is well-defended by missile defense systems may be emboldened to launch preemptive attacks on an adversary’s missile forces because its defenses could intercept any surviving missiles launched in retaliation. Moreover, if those defenses are limited—that is, if they can defeat a small-scale attack but not a large-scale one—the incentives for the state to preempt and ensure that an adversary cannot launch a large-scale attack can be particularly strong.

This ambiguity between offensive and defensive capabilities is being compounded by two trends in contemporary U.S. doctrine and technological advances. First, the United States is seeking to broaden the concept of missile defense to include both non-nuclear preemptive attack capabilities and defensive intercept capabilities. The former preemptive kind, colloquially known as left-of-launch attack operations, are intended to “neutralize offensive missile threats prior to launch” through kinetic strikes or nonkinetic means—such as directed energy weapons, cyber interference, and electronic warfare.56 Likewise, the United States seeks to build an Integrated Air and Missile Defense system that similarly embraces the concept of melding offensive and defensive capabilities into one “comprehensive joint and combined force,”57 so as to synchronize elements such as global missile defense and global strike that employ “all means to produce both lethal and nonlethal effects.”58 For China, the U.S. emphasis on integrating offensive and defensive capabilities indicates an increasingly aggressive approach to missile defense and a more offensive-minded military posture generally.

From a Chinese perspective, U.S. missile defense systems appear to be becoming increasingly offense-oriented, despite U.S. insistence that they are defensive.

Second, China believes the United States is growing more interested in developing and deploying dual-capable and/or multi-mission systems. (After all, some missile defense systems can inherently be used for more than one mission.) Some interceptors, for example, can be adapted for use as land-attack or anti-satellite (ASAT) weapons.59 Indeed, even some Chinese technical experts believe that dual-capable or multi-mission missiles represent a potential future trend in missile development.60 As for the U.S. military, the 2019 MDR report and senior Defense Department officials have shown growing interest in space-based interceptors. But Chinese experts view them as possessing significant offensive potential beyond traditional missile defense, including for counterspace and land-attack missions. In an interview published by the official newspaper of the Chinese Ministry of Science and Technology, one senior expert from the Beijing Institute of Space Science and Technology Information concludes future U.S. space-based interceptors will be a “big killer” weapon intended to conduct offensive attacks on ground-based targets from space.61

The United States may believe that Chinese experts misinterpret U.S. intentions in developing missile defense systems. But some U.S. activities only seem to validate such Chinese experts’ convictions. Perhaps most notably, the United States shot down one of its own satellites with an SM-3 interceptor in 2008. More recently, the SM-6 missile was reportedly described by the Missile Defense Agency as the “Swiss-Army knife of missiles,” being capable of conducting air defense, missile defense, and anti-surface warfare.62 Similarly, most Chinese experts share their Russian counterparts’ assessment that the Mk-41 launchers deployed in Europe, ostensibly for missile defense as part of the Aegis Ashore program, also can launch offensive missiles, such as land-attack Tomahawk cruise missiles.63

Some U.S. experts even urge the United States to build more multi-mission systems. Proposals include co-locating offensive and defensive capabilities; integrating missiles and interceptors into the same multiple launcher; using the SM-6 interceptor for land-attack; and equipping the SM-3 interceptor to function as a medium-range ballistic missile for anti-ship or land-attack missions.64 Although these suggestions come from U.S. scholars, Chinese experts generally believe that they likely reflect U.S. government thinking and future trends in U.S. policy. Such integrated capabilities could increase a weapon’s military effectiveness and operational flexibility, but doing so would further muddy distinctions between offensive and defensive weapons and would exacerbate Chinese concerns that missile defense cooperation between the United States and its allies, particularly Japan, could contribute to the allies’ offensive missile attack capabilities.65

To fully understand the sources of Chinese suspicions over U.S. missile defense objectives is challenging. But Chinese concerns about ambiguities pertaining to U.S. capabilities and policies are clearly genuine. In particular, uncertainties about the purpose of U.S. theater missile defense systems is likely to further complicate regional security dynamics in East Asia and potentially fuel an arms race of theater-range offensive missile systems. The potential for U.S. strategic missile defense to counter both North Korean and Chinese ICBMs is an issue worth studying jointly and could be a topic for substantive U.S.-China security dialogues. The issue of U.S. theater missile defense potentially contributing to strategic missile defense capabilities also warrants joint examination and candid discussions. These issues, due to their technical nature, tend to be less politicized and could perhaps jumpstart an effective dialogue.


1 For an in-depth analysis of the continuities and changes in U.S. missile defense policies, see James M. Acton, “US National Missile Defense Policy,” in Regional Missile Defense From a Global Perspective, edited by Catherine McArdle Kelleher and Peter Dombrowski (Stanford, CA: Stanford University Press, 2015).

2 U.S. Department of Defense, Office of the Secretary, Missile Defense Review Report, 2019.

3 Ibid.

4 The 2018 U.S. NPR report does not include similar language on the limited role of U.S. strategic missile defense.

5 “Remarks by President Trump and Vice President Pence Announcing the Missile Defense Review,” White House, January 17, 2019,

6 Ted Cruz, “Commentary From Sen. Ted Cruz: America Needs Space-Based Interceptors,” National Defense Magazine, April 10, 2019,; and Thomas Karako and Ian Williams, “Missile Defense 2020: Next Steps for Defending the Homeland,” Center for Strategic and International Studies, 2017.

7 Wu, [How to avoid a China-U.S. nuclear arms race].

8 For one example of such an acknowledgment by senior U.S. officials on how technical challenges and economic costs prevent the United States from building strategic missile defense capabilities against Russia or China, see Frank A. Rose, “Ballistic Missile Defense and Strategic Stability in East Asia,” U.S. State Department, speech at the Federation of American Scientists, Washington, DC, February 23, 2015,

9 Department of Defense, Ballistic Missile Defense Review Report, 2010, 13.

10 Wu, [How to avoid a China-US nuclear arms race].

11 Yu Hongjun (于洪君), “美国霸权的演进路径与中美关系的未来走势” [Evolving path of U.S. hegemony and future trends of the China-U.S. relationship], Theory and Reform (理论与改革) no. 3 (2019): 70–78.

12 Brad Roberts and Wu Riqiang, “Letters to the Editor,” Survival “Global Politics and Strategy” 56, no. 1 (2014): 211–213; and Wu, “China’s Anxiety About US Missile Defence: A Solution,” 29–52.

13 Tong Pu (童朴), “美新版导弹防御战略“落点”在哪” [What is the focal point of new U.S. missile defense strategy], PLA Daily (解放军报), February 14, 2019, 11.

14 U.S. Department of Defense, Office of the Secretary, Missile Defense Review Report, 2019.

15 Tong Zhao, “Conventional Challenges to Strategic Stability: Chinese Perspectives of Hypersonic Technology and the Security Dilemma,” in The End of Strategic Stability? Nuclear Weapons and the Challenge of Regional Rivalries, edited by Lawrence Rubin and Adam N. Stulberg (Washington, DC: Georgetown University Press, 2018).

16 James M. Acton, Silver Bullet? Asking the Right Questions About Conventional Prompt Global Strike (Washington, DC: Carnegie Endowment for International Peace, 2013).

17 John L. Dolan, et al., “Hypersonic Weapons Are Literally Unstoppable (as in America Can’t Stop Them), National Interest, May 15, 2019.

18 Wu Riqiang, “No Stability Without Limits on Missile Defense,” Bulletin of the Atomic Scientists, September 24, 2014.

19 U.S. Department of Defense, Missile Defense Agency, “Ground-based Midcourse Defense (GMD),”

20 George Lewis, “Ballistic Missile Defense: How Many GMD System Interceptors Per Target?,” May 23, 2012,

21 U.S. experts Hans M. Kristensen and Robert S. Norris estimated at the beginning of 2018 that North Korea possessed about five ICBMs that had been successfully flight-tested (the Hwasong-14 and Hwasong-15 models). See Hans M. Kristensen and Robert S. Norris, “North Korean Nuclear Capabilities, 2018,” Bulletin of the Atomic Scientists 74, no. 1 (2018). In its most recent public display of its ICBM stockpile during the country’s February 2018 military parade, North Korea showed a total of eight ICBMs (one of them was a backup unit) on transporter-erector-launchers or extended trucks, although it is possible that some of these were not real missiles. Taking into consideration the possibility that Pyongyang has continued to manufacture new ICBMs since early 2018, North Korea may possess about ten ICBMs as of 2019.

22 Matt Korda and Hans M Kristensen, “US Ballistic Missile Defenses, 2019,” Bulletin of the Atomic Scientists 75, no. 6, (2019): 295–306.

23 Kristensen and Korda, “Chinese Nuclear Forces, 2019.”

24 Wu, [How to avoid a China-US nuclear arms race].

25 U.S. State Department, Office of International Information Programs, “Missile Defense System Won’t Harm Russian Strategic Deterrent,” Washington File, June 23, 2000.

26 Daniel Wertz, “North Korea’s Ballistic Missile Program,” National Committee on North Korea, December 2017.

27 U.S. National Intelligence Council, “Foreign Missile Developments and the Ballistic Missile Threat to the United States Through 2015,” September 1999.

28 Brian Dunn, “A Technological Path Out of the Missile-Defense Security Dilemma,” Defense One, March 19, 2019,; James E. Goodby and Theodore A. Postol, “A New Boost-Phase Missile Defense System—and Its Diplomatic Uses in the North Korea Dispute,” Bulletin of the Atomic Scientists 74, no. 4 (2018): 210–219; and Dean A. Wilkening, “Airborne Boost-Phase Ballistic Missile Defense,” Science and Global Security 12, no. 1–2 (2004): 1–67.

29 Wilkening, “Airborn Boost-Phase Ballistic Missile Defense.”

30 Tong Zhao, Tides of Change: China’s Nuclear Ballistic Missile Submarines and Strategic Stability (Washington, DC: Carnegie Endowment for International Peace, 2018).

31 U.S. Office of Naval Intelligence, “The People’s Liberation Army Navy: A Modern Navy With Chinese Characteristics,” 2009.

32 Roberts and Wu, “Letters to the Editor.”

33 Wu, “China’s Anxiety About U.S. Missile Defence: A Solution”; and Wu Riqiang (吴日强), “朝美双向威逼与朝核危机的出路” [North Korea–U.S. mutual compellence and a solution to the North Korea nuclear issue], Contemporary International Relations (现代国际关系) no. 2 (2018): 18–24.

34 U.S. Department of Defense, Ballistic Missile Defense Review Report, 2010; and U.S. Department of Defense, Office of the Secretary, Missile Defense Review Report, 2019.

35 Both countries agreed that interceptors with burnout speeds greater than 7 kilometers/second are strategic interceptors, but they could not agree on the upper speed limit for theater missile interceptors. The Clinton administration proposed 5 kilometers/second as the upper speed limit, but Russia did not accept this proposal.

36 Admittedly, the financial cost of doing so would be prohibitively high.

37 He Yingbo and Qiu Yong, “THAAD-Like High Altitude Theater Missile Defense: Strategic Defense Capability and Certain Countermeasures Analysis,” Science and Global Security 11, no. 2–3 (2003): 151–202.

38 Lisbeth Gronlund, et al., “Highly Capable Theater Missile Defenses and the ABM Treaty,” Arms Control Today 24 (1994): 3.

39 Laura Grego, “The Anti-Satellite Capability of the Phased Adaptive Approach Missile Defense System,” Federation of American Scientists, 2011, 26–30.

40 Dean A. Wilkening, “Does Missile Defence in Europe Threaten Russia?,” Survival 54, no. 1 (2012): 31–52; and He and Qiu, “THAAD-Like High Altitude Theater Missile Defense: Strategic Defense Capability and Certain Countermeasures Analysis.”

41 Thomas Karako, Missile Defense and Defeat: Considerations for the New Policy Review (New York: Rowman and Littlefield, 2017).

42 National Research Council, Making Sense of Ballistic Missile Defense: An Assessment of Concepts and Systems for US Boost-Phase Missile Defense in Comparison to Other Alternatives (Washington, DC: National Academies Press, 2012).

43 Wang Shitao (王世涛) and Xing Xiaoli (邢晓莉), “韩国部署萨德系统对中国沿海弹道导弹影响浅析” [The effects of THAAD deployment on the ballistic missiles deployed along China’s coastal areas], Aerodynamic Missile Journal (飞航导弹) no. 9 (2016): 41–45; and Wu Riqiang (吴日强), “美国要在韩国部署“萨德”,对中国国家安全会有哪些影响?” [U.S. to deploy THAAD in South Korea: implications for China’s national security], Tengxun Jiangwutang (腾讯讲武堂),

44 Liu, [Analysis on U.S. plan to deploy THAAD system in South Korea].

45 Tong Zhao, “The Perception Gap in the THAAD Dispute—Causes and Solutions,” China International Strategy Review 2017, edited by Wang Jisi (Beijing: Peking University International Strategic Institute, November 2018).

46 “Midcourse Discrimination for the Phase One Strategic Defense System: A Report of the BMD Panel of the Army Science Board,” Federation of American Scientists, February 1989, 24–26,

47 Private conversation with a former U.S. senior official, October 2019.

48 Japanese Ministry of Defense, Defense of Japan 2018 (Tokyo: Japanese Ministry of Defense, 2018).

49 Kevin Pollpeter and Kenneth W. Allen, “The PLA as Organization v. 2.0,” Defense Group Inc., 2015.

50 David E. Sanger and Michael R. Gordon, “U.S. May Soon Increase Pressure on China to Constrain North Korea,” New York Times, March 15, 2017.

51 Hu, [Impact of the U.S. theater missile defense system in East Asia on China’s national security].

52 Kristensen and Norris, “Chinese Nuclear Forces, 2018.”

53 U.S. Department of Defense, Office of the Secretary, Annual Report to Congress: Military and Security Developments Involving the People’s Republic of China 2019.

54 This analysis does not take into account the scenario in which China would preemptively use nuclear weapons first in a conventional conflict. Open-source evidence based on PLA military strategy, operational doctrine, training scenarios, and military exercises indicates that China is serious about abiding by its NFU policy.

55 Alexey Arbatov, “Mad Momentum Redux? The Rise and Fall of Nuclear Arms Control,” Survival 61, no. 3, (2019): 7–38.

56 James Syring, “Unclassified Statement of Vice Admiral J.D. Syring, U.S. Navy, Director, Missile Defense Agency,” Senate Armed Services Committee Subcommittee on Strategic Forces, April 13, 2016; and U.S. Department of Defense Office of the Secretary, Missile Defense Review Report, 2019.

57 Martin E. Dempsey, “Joint Integrated Air and Missile Defense: Vision 2020,” U.S. Joint Chiefs of Staff, 2013; and Stefan Soesanto, “US Missile Defense in the Age of Everything: From BMDs to IAMD,” Pacific Forum Issues and Insights 16, 2016.

58 U.S. Joint Chiefs of Staff, “Countering Air and Missile Threats,” Joint Publication 3-01, April 21, 2017,

59 Chen Li (陈丽) and Xue Hui (薛慧), “陆基宙斯盾系统反导能力研究” [Analysis of the missile defense capabilities of the land-based Aegis system], Aerodynamic Missile Journal (飞航导弹) no. 12 (2018): 73–77; and Yan, [Theater missile defense systems and Northeast Asian security].

60 Xiong Benyan (熊本炎), “多用途导弹:化繁为简大势所趋” [Multi-mission missile: general trend for the future to reduce complexity], China Aerospace News (中国航天报), August 19, 2017, 3.

61 Yu Ziyue (于紫月), “天基反导并非固若金汤” [Space-based missile defense is not invincible], Science and Technology Daily (科技日报), August 8, 2018, 5.

62 Raytheon, “One Missile, Many Missions: Raytheon’s Standard Missile-6,” Breaking Defense, January 2019,

63 “军事专家解析:陆基“宙斯盾”加装“战斧-4”有多可怕?” [Military experts explain the consequences of Aegis Ashore being armed with Tomahawk-4], CCTV, February 14, 2019,; and

Lan Shunzheng (兰顺正), “美国退出《中导条约》——又一道“限速器”被打开”

[U.S. withdrawal from INF Treaty: breaks another speed bump], FT Chinese (FT中文网), October 24, 2018.

64 Thomas Karako and Wes Rumbaugh, “Distributed Defense: New Operational Concepts for Integrated Air and Missile Defense,” Center for Strategic and International Studies, January 2018.

65 Hu, [Impact of the U.S. theater missile defense system in East Asia on China’s national security].