Source: Bulletin of the Atomic Scientists
At the March 19 hearing of the Senate Armed Services Committee, Adm. Cecil Haney, commander of the US Strategic Command, said “China is … moderniz[ing] its strategic forces by enhancing existing silo-based ICBMs, conducting flight tests of a new mobile missile, and developing a follow-on mobile system capable of carrying multiple warheads.”
The Pentagon’s annual reports to Congress on China’s military and security developments have also indicated that China has an interest in developing technology for MIRVs (multiple independently targeted reentry vehicles.) If the information is correct—much is still to be corroborated—then it is cause for some serious policy discussions.
Existing Chinese nuclear missiles are believed to have one single warhead on top of each missile. A MIRVed missile, however, would be armed with multiple warheads, allowing a single missile to hit a number of different targets at once, or hit a single target with multiple warheads. Such an arrangement would also make MIRVs harder to knock out with anti-missile technology.Reports about which missile system or systems might ultimately feature MIRV capability are necessarily speculative. But based on unconfirmed reports in Defense News and GlobalSecurity.org, MIRV technology is suspected to have been tested on the DF-41, the DF-31B, and the DF-5B. Some organizations, such as GlobalSecurity.org, suggest that the new JL-2 submarine-launched ballistic missile is capable of carrying MIRV warhead technology as well. And on March 3, IHS Jane’s Defence Weekly published what it claimed were photos of a large, MIRV-equipped, Chinese ICBM that had been gleaned from Chinese military web pages on the Chinese Internet. While admittedly there are many great uncertainties, these murky bits and pieces constitute hints that China may be seriously researching and developing MIRV capability.
MIRV technology is controversial because it can potentially destabilize the nuclear balance by creating incentives to strike first. One important question is what motivates China to research and develop a MIRV capability. And if China does make a decision to ultimately deploy the technology, what might the implications be for strategic stability?
Whither Goest China?
China’s interest in MIRV capability is a sensitive one inside the country. But outsiders can glean a sense of the Chinese perception of the usefulness of MIRV technology by looking at articles written by Chinese scientists within the aerospace industry (original in Chinese). These articles strongly indicate that China’s approach is shaped by their scientists’ close analyses of what other major nuclear powers are doing with their respective MIRV programs. It seems that in pursuing MIRV technology, China is merely following in the footsteps of others.
Past efforts to limit MIRV missiles through arms control met with limited success. The second round of the Strategic Arms Limitation Talks, as well as START I, both included provisions for limiting MIRV-capable missiles, and START II was the first agreement to envision a complete ban of all land-based MIRV missiles. But neither SALT II nor START II entered into force. And the most recent arms reduction treaty, New START, does not place any explicit limitations on the development or deployment of MIRV systems—reflecting a lack of consensus in this regard.
Citing the potentially destabilizing effect of the country’s MIRVed silo-based ICBMs, the Obama administration’s 2010 Nuclear Posture Review announced a plan to “de-MIRV” all US Minutemen III ICBMs, a process completed in June 2014. But while its land-based ICBMs are no longer deployed with multiple warheads, the United States still maintains a submarine-launched MIRV force, which it shows no interest in de-MIRVing. In addition, the United States is committed to maintaining the capability to re-MIRV its ICBMs if strategic security conditions warrant. Indeed, the US Congress explicitly required the maintenance of such capabilities, while reports from organizations such as the Global Security Newswire indicate that there's a desire on the part of the United States to retain MIRV capability on the planned follow-up to the Minuteman III ICBM.
All of this is seen by Chinese analysts as evidence that MIRV technology is the inevitable wave of the future.
Chinese analysts have also been closely following Russia’s nuclear forces, which are even more heavily MIRVed than America’s. Current Russian MIRVed systems include mobile- and silo-based versions of the “Yars” SS-27 Mod 2, the silo-based SS-18, the silo-based SS-19, and all Russian submarine-launched ballistic missiles. Russia’s extensive ongoing modernization program underscores the even greater importance of MIRV technology for future Russian systems. All new Russian strategic deployments are expected to be MIRVed. The new Russian SS-27 ICBM Mod 3 (NATO and Russia use different designations for the same missile systems; Russia calls this weapon the “RS-26”) expected to be deployed in 2016, will reportedly be able to carry up to four warheads, says the Union of Concerned Scientists.
Additionally, the Hudson Institute expects Russia to begin production of a 100-ton, silo-based, liquid-fueled MIRV-capable ICBM known as the Sarmat. Indeed, based on reported planned deployments, Hans Kristensen of the Federation of American Scientists predicts that “Although Russia by 2022 will deploy fewer ICBM warheads, roughly 90 percent of them will be multiple independently targetable reentry vehicles.”
Besides the two nuclear superpowers, the strategic missiles of both France and the United Kingdom are MIRVed as well. This has led Chinese experts to conclude that “nowadays, all the intercontinental strategic missiles being developed and which will be developed in the future by all major nuclear powers employ the multiple independently targetable warheads technology” (original link in Chinese). Facing a fluid strategic security environment with many emerging technological challenges, China may feel that the safest way to minimize uncertainties and reduce risks is to follow the path of other nuclear powers in developing capabilities which—while of moderate strategic value today—might be beneficial or even vital in the future.
No less important, China views MIRV capability as necessary to retaining a credible nuclear deterrent in the face of perceived new challenges to force survivability, especially missile defense. Due to its relatively small arsenal and low alert levels (China does not have a launch-on-warning policy and is believed to have warheads unmated and stored separately from missiles in peacetime), the credibility of China’s nuclear deterrent is often questioned. Some American analysts have even gone so far as to suggest that China’s nuclear arsenal would not survive a nuclear first strike from the United States, or even a conventional first strike.
Uncertain Versus Assured Retaliation
Consequently, Chinese scholars such as Wu Riqiang have argued that China’s current nuclear deterrent is based on “uncertain retaliation” and so the country should be interested in a future deterrent based on “assured retaliation.” Well before China achieves the latter goal, MIRVs can influence the risk-benefit calculations of potential adversaries by dramatically increasing the retaliatory power of any surviving Chinese missiles, therefore increasing the credibility of the threat of “uncertain retaliation.”
More importantly, persistent American investment in missile defense is also motivating China to develop MIRV capability. MIRV technology has long been a technically feasible option for China. By 1990, China had acquired the ability to launch multiple satellites into distinct orbits from a single rocket, a technological feat that in many ways mirrors that of deploying multiple warheads from a single missile. Despite obtaining this nascent ability, developing and deploying MIRVed missiles did not appear to be a top priority for the country's rulers. However, with the United States reinforcing its commitment to missile defense over the last decade, more Chinese experts are drawing connections between MIRVs and missile defense.
MIRVed missiles are especially useful for dealing with nuclear-tipped interceptors, because MIRVed missiles force the defender to detonate multiple nuclear interceptors in relative proximity to each other—which may in the end unintentionally destroy the defender’s other interceptors as well, an effect known as “nuclear fratricide."
But given that today’s missile interceptors are not nuclear-armed, but simply use the kinetic energy from a direct impact to destroy an incoming warhead, MIRVed missiles probably do not provide a better chance of defeating an opponent’s missile defenses than the simultaneous release of a large number (or “salvo launch”) of single-warhead missiles.
Still, one MIRVed missile can achieve the same result as many single-warhead missiles—and offers the bonus of being cheaper to build, once the technology has been mastered.
In theory, the United States could respond to China’s MIRVed missiles by deploying interceptors that can hit the Chinese missiles during either the initial boost phase or shortly afterwards, before their warheads are released. (In the boost phase—earliest stage of a missile’s flight—the missile’s booster is actively engaged and the missile is gaining velocity. During this period, neither the warheads nor the “bus” on which they are mounted have been released from the missile body, making it an especially attractive target because all the warheads are still grouped together.)
But developing interceptors that can knock out incoming missiles in their boost phase is much more technologically challenging than contemporary systems which target incoming missiles at a later stage of flight. And their deployment requires the interceptor to knock out an incoming missile so early in its flight that the incoming missile is barely off the ground—which in turn means that the interceptor must strike very fast indeed, or be very close to the launchsite to begin with.
The latter strategy imposes significant geographical constraints; if the United States were to successfully develop boost-phase interceptors, they would need to be deployed far forward, on land or in waters close to China. Such deployment would make them vulnerable to China’s growing capability to neutralize enemy assets deployed close to China’s coast. As a result, the Chinese increasingly see MIRVs as a necessary countermeasure (original link in Chinese) to the prospective further buildup of US missile defense.
That said, there are different opinions among experts in the Chinese technical community about the usefulness of MIRV technology. For example, an engineer from the Research and Development Center of China Academy of Launch Vehicle Technology argued that “the penetration capability, survivability, and overall effectiveness of MIRVed missiles is nowhere near that of a salvo launch of single-warhead missiles with the same number of warheads” (original in Chinese). (It should be noted that the total number of openly available publications on this subject is very small, and we consider that even one strong and open opposition piece from an insider shows a lack of internal consensus.)
Meanwhile, non-Chinese media and government reports strongly indicate that despite China’s on-going research and development program in MIRV, there is no evidence of a decision to actually deploy the technology, should it be created. There is some historical precedent for this approach; there were instances in the past where China developed certain types of strategic military technologies but never deployed them: China's neutron bomb is a prime example.
Impact on Strategic Stability
Traditional wisdom holds that MIRVed ICBMs undermine stability for two reasons. First, MIRVed missiles greatly increase one’s first-strike capability against an adversary’s forces, thus potentially inviting a preemptive strike. Second, a MIRVed missile loaded with a large number of warheads is a tempting target; if the warheads’ owners believe that they are threatened by an enemy first strike, then there is a greater incentive to fire them first before they can be wiped out on the launchpad. This “use it or lose it” dilemma is one of the fundamental problems with MIRVed ICBMs.
Consequently, the effects of Chinese MIRVed missiles on strategic stability depend on how they are deployed (if, indeed, they are ever deployed). The existence of different opinions among Chinese experts indicates that there is still room for debate about specific deployment strategies. Some of them are less destabilizing than others.
The most obvious concern from the perspective of potential adversaries is the potential for China to significantly increase the number of nuclear warheads deployed on its MIRV-capable missiles. According to the Belfer Center’s Hui Zahng, China’s limited fissile material stockpile means that the country does not have the ability to build significantly more warheads without restarting fissile material production.
China’s nuclear doctrine may also not call for the need to equip all of its MIRV-capable missiles with multiple warheads. One option, therefore, is to keep the current small stockpile of warheads unmated from missiles and to store them in separate locations during peacetime, joining the warheads to those missiles that survive after an enemy’s first strike. In this way, MIRV-capable missiles increase China’s second strike capability but do not necessarily require a significant buildup of total nuclear warheads.
In addition, because China’s primary objective in developing MIRV capability is to counter potential missile defenses, another option is to put one real warhead and several heavy dummy warheads on each missile, instead of multiple real warheads. These dummy warheads can be made to have the same weight, shape, and other physical characteristics as real warheads.
Decoys, Dummies, and Chaff
There are benefits to using such heavy dummy warheads as opposed to the more common and lighter “decoys.” Russia, the United Kingdom, and the United States have all deployed decoys that weigh considerably less than real warheads. Such decoys are easier to distinguish from real warheads, especially during the reentry phase when the lighter decoys slow down much more rapidly than real warheads due to the effects of atmospheric drag.
These states did not deploy heavy dummy warheads because they would have taken up valuable payload capacity from real warheads. However, because China is interested not in expanding the size of its nuclear arsenal but in countering missile defense, this problem is not a concern for Beijing. Using MIRV technology to deliver dummy warheads would strengthen China’s second-strike capability—and its presence could be publicly announced without compromising any Chinese security interests.
The alert status of China's MIRVed ICBMs also matters. If China in the future chooses to arm each of its missiles with multiple real warheads, then countries such as India may be concerned about the potential increase in China’s first-strike capability against them. China at present is believed to have adopted a practice of not mating nuclear warheads to their ICBMs during peacetime. If China continues this practice and keeps warheads unmated and separate from future MIRV-capable ICBMs, that may help to reduce other countries’ concerns about an out-of-the-blue, devastating first strike from China, by demonstrating that China has no intention of keeping its nuclear missiles ready to launch in a very short time with little advance warning.
During a crisis, from an adversary’s perspective, an ICBM deployed with multiple warheads presents a far greater threat than a single-warhead missile. If China deploys MIRV systems in the future, it ought to be extremely sensitive about the potential escalation risks associated with the operations of MIRVed missiles during a crisis. A decision to raise alert levels and mate warheads with such missiles could send a stronger signal of escalation than doing so with single-warhead missiles. MIRVed missiles on higher alert are also more likely to invite preemptive strikes. As a result, raising alert levels could have unintended consequences beyond the aim of demonstrating political resolve—the military implications are much greater than before and are more easily subject to misinterpretation by potential adversaries. These risks need to be taken into consideration by Chinese decision-makers when they consider the role of any future MIRVed missiles.
A final consideration is which delivery system to equip with multiple warheads. If China decides to go ahead and deploy MIRV capability, it should consider what deployment options pose the least risk. It makes sense to put MIRVed missiles on the most survivable platforms. The American, Russian, British, and French practice of deploying MIRVed missiles on nuclear submarines is generally not considered destabilizing because their nuclear-missile-equipped submarines are very survivable—much more so than their silo-based ICBMs or strategic bombers. This may or may not be true in China’s case. Chinese nuclear-missile-equipped submarines have a shorter development history and need much more work to enhance their survivability, such as lowering their noise levels. In comparison, Chinese mobile ICBMs may be more survivable than China’s nuclear-missile-equipped submarines and silo-based ICBMs in the near term.
Consequently, Chinese decision-makers will face tradeoffs when deciding how to deploy MIRVed missiles. For instance, silo-based ICBMs are less survivable but can accommodate heavier missiles that can potentially carry more warheads. Mobile ICBMs, on the other hand, are more sensitive to weight limitations and, as they become heavier, they also become less mobile and less survivable.
At the end of the day, the ultimate goal of the Chinese MIRV program should be to increase the credibility of the country’s deterrent and to maintain—perhaps even enhance—regional strategic stability. Assuming China has a research and development program for MIRVs, in deciding whether and how to deploy and manage any future MIRV capability, China’s decision-makers ought to place top priority on options that will enhance both deterrence and strategic stability, and avoid options that may undermine either.
This article was originally published the Bulletin of the Atomic Scientists.