Table of Contents

Given that China seems to be developing sea-based nuclear weapons mainly to strengthen its second-strike capability, the country’s SSBNs by themselves should not pose a radically new security threat to any country. That said, countermeasures to China’s SSBN program undertaken by the United States and other countries as well as Chinese efforts to protect its SSBNs could still foster unstable crisis and arms race dynamics. Beijing, Washington, and other regional parties should, therefore, aim to mitigate these negative interactions and contain their impact on regional security.

As in the case of the escalation risks associated with encounters between SSBNs and ASW assets, the historical record of the Cold War provides useful lessons for how to mitigate these risks. Indeed, Soviet and U.S. scholars explored various potential risk-mitigation measures. Some of their efforts focused on the possibility of formal arms control agreements designed to reduce the threat posed to SSBNs and to minimize the risks of confrontational encounters. These measures included prohibiting the use of active sonar, prohibiting the construction of extensive underwater hydrophone systems, establishing SSBN sanctuaries, and limiting the number of deployed attack submarines.

Unfortunately, the U.S. and Russian governments never endorsed these formal arms control proposals. Some of the measures would have entailed formidable verification challenges or contradicted the U.S.-supported principle of freedom of navigation. Some of them would have imposed restrictions that would have seriously undermined civilian or legitimate activities by third parties. Others would have benefited the two states unequally.1

Countermeasures to China’s SSBN program undertaken by the United States and other countries as well as Chinese efforts to protect its SSBNs could still foster unstable crisis and arms race dynamics.

This historical experience suggests that any practical efforts to reduce the escalation risks associated with encounters between SSBNs and ASW assets cannot start with formal arms control measures that demand stringent and complex verification regimes. Furthermore, these efforts should avoid unintended interference with third party activities and should offer mutual benefits to all parties involved. Given these constraints, China, the United States, and U.S. allies should focus first on modest but practical confidence-building measures instead. Such steps should start with reassurances about each side’s strategic intentions, placing self-imposed limits on potentially escalatory activities, and establishing confidence-building measures and clear rules of the road for maritime encounters.

A U.S. Political Commitment to Restrain Strategic ASW

One important step the United States can take is to commit to refraining from conducting strategic ASW against Chinese SSBNs. U.S. political leaders should not let the country’s military make decisions about whether the United States should develop a strategic ASW capability against China, because such a military-driven decision would likely be based on tactical incentives or problematic assumptions about escalation control. On this critical issue, U.S. political leaders need to provide clear top-down guidance to players at the operational level.

Some U.S. experts have acknowledged that conducting strategic ASW against the Soviet Union during the Cold War was a problematic strategy and that repeating this strategy against Chinese nuclear-armed submarines today would be counterproductive. After analyzing U.S. strategic ASW policies against the Soviet Union during the 1980s, for instance, the U.S. political scientist Barry Posen concluded that “political management” was needed on this issue to avoid a catastrophe.2 Similarly, U.S. decisionmakers today need to recognize that, because of the risks of escalation, in particular, developing a strategic ASW capability against China does not serve the strategic interests of the United States. U.S. political leaders must ensure that the U.S. Navy’s actions reflect this decision.

One important step the United States can take is to commit to refraining from conducting strategic ASW against Chinese SSBNs.

There is some question of what form such a U.S. political commitment would take. Ideally, the United States would state publicly that it is not in the national interest to conduct strategic ASW against China and that the U.S. military does not and will not do so. If an open declaration is not possible, Washington could convey this message in private meetings with Chinese decisionmakers. Such a political commitment would not completely address Chinese concerns, but it would help mitigate them and could provide an incentive for China to refrain from adopting aggressive SSBN operation strategies, such as pre-delegating launch orders, keeping as many SSBNs as possible on patrol during peacetime, or employing overly aggressive pro-SSBN tactics.

That said, the U.S. government has been reluctant to openly acknowledge mutual nuclear vulnerability with respect to China, not least because of concerns that such an acknowledgment could undermine the credibility of extended nuclear deterrence commitments to U.S. allies. A fallback option would be for Washington to publicly recognize the role of China’s sea-based nuclear forces in enhancing strategic stability. Such an acknowledgment might go some way to clarifying U.S. intentions and mitigating Chinese concerns. Moreover, this second option would not constitute a significant departure from existing U.S. policy, given that the United States has long viewed its own SSBN forces as playing an important role in maintaining strategic stability.

Main Policy Takeaways

  • U.S. political leaders should decide against pursuing strategic ASW against China and give clear guidance to the military on that basis.
  • Ideally, the United States should openly declare—or else state privately—that it is not in the U.S. interest to conduct strategic ASW operations against China and that the United States will not do so.
  • If that is not possible, the United States should acknowledge that it recognizes the role of China’s sea-based nuclear forces in enhancing strategic stability.

Chinese Transparency Measures to Reduce Foreign Threat Perceptions

For its own part, Beijing should convey a clear message to the United States and the rest of the international community that the addition of sea-based ballistic missiles to China’s nuclear arsenal is aimed only at maintaining a credible second-strike capability and that SSBNs do not and will not change China’s overall approach to nuclear weapons. Beijing should emphasize that it will stick to its long-standing principle of possessing a “lean and effective” nuclear arsenal, a commitment made in China’s previous defense white papers.

Despite a tradition of maintaining a high degree of secrecy about its nuclear capabilities, China has become somewhat more transparent in recent years about some of its capabilities, particularly its SSBNs.3 Official press reports about SSBN activities have become more frequent. PLA- and government-affiliated experts frequently discuss relevant developments on official television programs. SSBNs have made more frequent appearances in China’s large-scale maritime military parades. Additionally, China has unveiled advanced submarine building facilities. Meanwhile, unofficial but detailed information about SSBNs is widely discussed on the internet and social media platforms, without being blocked by the government. This modest increase in Chinese transparency represents a positive trend that has been largely motivated by a perceived need to enhance deterrence.

Beijing should convey a clear message . . . that the addition of sea-based ballistic missiles to China’s nuclear arsenal is aimed only at maintaining a credible second-strike capability.

Now, in addition to showcasing its growing capabilities, China should consider how it can reassure other countries—especially the United States—about its defensive, peaceful intentions to forestall overreactions. To this end, China could make the purpose of its growing SSBN forces clearer to mitigate U.S. concerns that these forces could be used for aggressive purposes or could enable Beijing to adopt a less restrained nuclear posture. Greater Chinese transparency about its SSBN forces would help address U.S. concerns about Chinese strategic intentions or operational doctrines and would, therefore, reduce U.S. incentives to pursue preventive activities to counter Chinese SSBNs.

Specifically, China could seek to reassure the United States and its allies about the limited nature of its long-term SSBN development plans. China’s introduction of four 094-class SSBNs has already almost doubled the total number of Chinese ballistic missile launchers capable of reaching the U.S. homeland (recall figure 1). An unknown number of additional 094-class SSBNs are under construction, even as China is developing a next generation 096 class of SSBNs. Not only is the total planned number of this new class of SSBNs unknown, but it is possible that the 096-class submarine will carry more SLBM launchers than the 094-class model. Moreover, some analysts have speculated that these SLBMs will be armed with multiple independently targetable warheads.4 Given these developments, it is unsurprising that foreign experts worry about the rapid expansion of China’s SSBN forces and the potential that this expansion will lead to significant changes in China’s overall nuclear capabilities and posture.

To reduce such foreign concerns, Beijing might not have to reveal the precise number of SSBNs it intends to build or disclose detailed technical capabilities about its SSBNs, although such information would be helpful. A more feasible approach would be for China to declare the operational requirements for its SSBN fleet. To this end, China could consider outlining the key factors taken into consideration when Beijing decides the qualitative and quantitative requirements for building a survivable SSBN fleet. Such information would help China demonstrate that its SSBN development is not open-ended, is not driven primarily by the availability of resources, and is guided by clear and defensive principles.

Such limited disclosures would help Beijing stress the important connection between developments in foreign strategic ASW capabilities and those of China’s own SSBN fleet. In this sense, any relevant information China can provide would offer incentives for other countries to work with Beijing to address its security concerns. For example, given the view of some U.S. experts that Washington needs to build more SSNs to counter China’s growing SSBN capability, it would be in both countries’ interest to talk candidly about their respective programs so as to avoid an arms race based on worst-case assumptions.5

Main Policy Takeaways

  • China should explicitly declare that its SSBN fleet is aimed only at maintaining a credible second-strike capability and that it will not change China’s overall approach toward nuclear weapons.
  • Beijing needs to reassure the international community that its SSBN development is not open-ended or primarily driven by the availability of resources, but instead is guided by clear and defensive principles.
  • China should consider revealing the operational requirements for its future SSBN fleet, that is to say, the key factors that Beijing takes into consideration in deciding the qualitative and quantitative requirements for building a survivable fleet.

Joint Efforts to Build Confidence About ASW Operations

If the United States were willing to refrain from conducting strategic ASW against China, it would still face the challenge of distinguishing Chinese SSBNs from Chinese attack submarines. China would surely not enact far-reaching measures of its own, such as declaring separate operating areas for its SSBN and attack submarines, to help U.S. personnel draw this distinction clearly. China’s level of interest in making its SSBN operations distinguishable would be very much influenced by its degree of confidence in the U.S. commitment not to deliberately undermine China’s SSBN forces.

If the two countries could build some mutual confidence, there are additional measures both sides could take to further reduce the risks of potential misunderstanding and inadvertent escalation. The two states could start discussing whether there are realistic steps that China could take to make attack submarines and SSBNs more distinguishable without undermining their survivability. For instance, Beijing could refrain from allowing its attack submarines to use sound simulators that mimic SSBNs.6 (It is not known publicly whether China has developed or deployed such a technology but, if it has not yet, it may do so in the future.) Potential Chinese commitments like this would not be technically verifiable, but they could help demonstrate to the United States that China recognizes the security benefits of making nuclear and non-nuclear forces distinguishable. Such steps could be implemented as part of mutual cooperative efforts to increase operational transparency.

For its part, Washington should seek to make its tactical ASW operations less likely to be mistaken for strategic ASW activities. For instance, the United States could refrain from large-scale deployments of ASW forces in the South China Sea when U.S. carriers or other high-value surface ships are not present. The deployment of major ASW assets can be justified if high-value U.S. surface ships are operating in Chinese coastal waters where they might be threatened by Chinese attack submarines. But if such surface ships are not present—and they sometimes are not—China could reasonably infer that large-scale U.S. ASW deployment would be targeting its SSBNs.

Beyond the issue of distinguishability, the United States should avoid deliberately threatening Chinese SSBNs for the purpose of distracting Chinese attack submarines. That U.S. approach against the Soviet Union during the 1980s was thought to be a suboptimal way of achieving the goal of protecting SLOCs in the Atlantic Ocean.7 Using this tactic against China would be a recipe for both short-term crisis instability and long-term arms race instability. The more that U.S. operations appear to threaten Chinese SSBNs—for whatever reason—the more anxious Chinese decisionmakers will be, increasing the risks of escalation in a conflict. In the long run, such U.S. tactics would only encourage China to build more SSNs to protect its SSBNs and to conduct other offensive missions.

In addition, the United States should consider refraining from deliberately disrupting the C3 systems associated with Chinese SSBNs. In recent years, China has shown reasonable concerns about the reliability of these systems, especially their potential vulnerability to outside interference.8 A leaked classified document produced by the U.S. National Security Agency in 2001 acknowledges the United States’ “ability to acquire and locate signals associated with PRC submarines.”9 Furthermore, this document claims that the United States has “knowledge,” derived from signal intelligence, of the “organization, platforms, missile testing operations, and communications” associated with China’s SLBM program.

If the communications channels associated with Chinese SSBNs are vulnerable to interception, they may be vulnerable to interference too. Indeed, there have been reports that, on an unknown date, U.S. airplanes, including an EA-6B electronic warfare aircraft, disrupted communications with a Chinese nuclear submarine (probably an SSN) that was participating in a military exercise in the Yellow Sea, after the submarine had been tracked by a U.S. anti-submarine aircraft.10 Chinese electronic communications and combat systems were paralyzed, leading China to scramble fighter jets from its naval aviation forces to intercept the U.S. electronic warfare aircraft. Because Chinese SSNs and SSBNs may share the same communications systems, or similar ones, this incident has fueled Chinese concerns about apparent U.S. interest in interfering with its SSBN communications and its ability to actually do so.

In peacetime, U.S. efforts to explore potential vulnerabilities in the C3 systems of Chinese SSBNs would exacerbate Beijing’s suspicions that Washington is not really committed to bilateral strategic stability and instead is seeking to neutralize China’s nuclear deterrent. This suspicion could fuel a long-term arms race that benefits no one. During a crisis, U.S. efforts to interfere with the C3 systems of Chinese SSBNs could lead Beijing to suspect that Washington may be about to launch a disarming first strike, which could then prompt China to initiate escalatory countermeasures preemptively.

Until China has built dedicated and distinguishable C3 systems for the SSBN fleet that are separate from the C3 systems used by SSNs, the United States may need to exercise precautions against interfering with such shared C3 systems across the board. This would undermine some of the U.S. tactical ASW capabilities under certain circumstances, but given the escalation risks, it may still be worth considering.

Main Policy Takeaways

  • The United States and China should discuss whether there are other realistic ways for Beijing to make its attack submarines and SSBNs more distinguishable without undermining their survivability and for Washington to make its tactical ASW operations less likely to be mistaken for strategic ASW.
  • Washington should refrain from large-scale deployments of ASW forces in the South China Sea when U.S. carriers or other high-value surface ships are not present.
  • The United States should avoid using the tactic of deliberately threatening Chinese SSBNs to prevent Chinese attack submarines from being able to conduct offensive operations. Similarly, Washington ought to refrain from deliberately disrupting the C3 systems associated with China’s nuclear forces.

Joint Efforts to Establish Clear Rules of the Road

Clear rules for maritime encounters between the naval vessels of China, the United States, and other regional actors that build on previous guidelines would be beneficial for strategic stability. Unfortunately, existing maritime safety rules—both multilateral and bilateral ones—do not easily apply to submarine operations due to the extreme secrecy of these underwater vessels. That said, established rules do have implications for the general-purpose forces used to track or protect SSBNs. Reducing the likelihood of confrontations between ASW forces and those used to protect SSBNs could help lower the risks of escalation in the waters of the Asia Pacific, particularly in the South China Sea.

Relevant stakeholders—especially the United States and China—should, therefore, seek to negotiate clear rules concerning the interactions of such forces, including surface vessels and aircraft. U.S. and Chinese military leaders managed to make initial progress in 2014 and 2015 by establishing basic rules of behavior for unplanned surface-to-surface and air-to-air encounters.11

Clear rules for maritime encounters between the naval vessels of China, the United States, and other regional actors that build on previous guidelines would be beneficial for strategic stability.

Nonetheless, these rules are probably too general and abstract to prevent dangerous encounters between the two militaries. For instance, according to these rules, the “actions that the prudent commander (commanding officer) or master general should avoid” include “aerobatics” and the “unsafe approach” of one vessel to another.12 But these terms are not defined. As a result, such general statements have not been very effective at reducing the frequency of dangerous encounters in the past couple of years.

To reduce escalation risks substantially, the two militaries need to build on the 2014 and 2015 agreements by drafting more detailed rules. Although attack submarines sometimes play an important role in both ASW and SSBN-defense operations, it might be unrealistic—given the extremely secret nature of their operations—to include them in any set of rules in the near term, as desirable as it would be to do so. That said, private conversations with senior U.S. naval officers indicate that closed-door discussions between U.S. and Chinese experts about cooperative measures to enhance safe submarine operations are both necessary and feasible.13

In addition, the United States and China should start discussions on establishing rules of the road for new potentially destabilizing technologies. The increasing use of unmanned systems is a case in point. Advanced UUVs and USVs could potentially threaten the survivability of SSBNs, especially as sensor technologies improve. Moreover, UUVs and USVs are useful for disrupting the operations of forces that defend or threaten SSBNs. China’s view is that, under international maritime laws, the status of unmanned vehicles, including any entitlement to sovereign immunity from foreign jurisdiction, is unclear.14 This leaves significant room for a country to use or attack unmanned vehicles without effective constraints.

Because both the United States and China are making major investments to develop unmanned vehicles, the two countries’ share an interest in jointly exploring possible rules of the road to regulate the activities of unmanned vehicles and their interactions with manned systems. At the minimum, Beijing and Washington can start discussing what the legal status of unmanned vehicles should be, when UUVs should be legally protected from meddling by other countries, and what improvement can be made to current international laws to address such new concerns.

Ideally, rules would be negotiated in the near future before UUVs are deployed en masse. To this end, the two militaries could conduct tabletop exercises during official and/or unofficial dialogues to elicit more nuanced understandings about the potential risks associated with various employment strategies. Insights gained from such exercises could be used to help develop unilateral and cooperative risk-reduction measures. In addition, once armed UUVs are deployed, confidence-building measures—such as commitments to exercise unilateral restraint in using UUVs to conduct hold-at-risk operations against SSBNs—would be very helpful.

Main Policy Takeaways

  • China and the United States should seek to negotiate more detailed and specific rules to regulate interactions between U.S. ASW forces and Chinese general-purpose forces used to protect SSBNs.
  • U.S. and Chinese experts should conduct private discussions about cooperative measures to enhance safe submarine operations.
  • The two countries should initiate discussions to jointly explore possible rules of the road to regulate the activities of UUVs and USVs and their interactions with manned systems.
  • The U.S. and Chinese militaries could conduct tabletop exercises in official and/or unofficial dialogues to develop more nuanced understandings of the potential risks associated with various UUV employment strategies to stimulate the development of risk-reduction measures.

Chinese Reassurances to Other Regional Players

The United States and China are not the only stakeholders in the Asia Pacific, and Beijing should seek to reassure other regional countries. Given that Chinese SSBNs currently operating in China’s coastal waters cannot directly threaten the U.S. homeland, some U.S. allies—Japan and South Korea, in particular—might worry that they are potential targets. After all, in a hypothetical war over Taiwan—the most likely scenario for a serious U.S.-China military conflict—the United States would need logistical support from Japan and South Korea (among other allies). Tokyo and Seoul may worry that China would attempt to deter them from providing such support by threatening a nuclear attack. From Beijing’s perspective, such concerns are unfounded, because such a threat would directly contradict China’s unconditional NFU policy and its commitment to never threaten non-nuclear-weapon states with nuclear weapons. In light of these considerations, China should be willing to explicitly rule out nuclear attacks on Japan and South Korea.

Aside from fears stoked by China’s nuclear weapons themselves, forceful Chinese operations to protect its SSBNs in the South China Sea could be seen by other regional countries, including ASEAN members, as evidence of China’s aggressive or expansionist policies. Such perceptions could motivate these countries to align more closely with the United States in an effort to balance China. It is, therefore, in China’s interest to show that it is not pursuing a comprehensive sea-control capability in the region, but instead is simply aiming to achieve the limited defensive goal of protecting its sea-based nuclear deterrent capabilities from the United States.

Beyond formulating clearer rules with the United States to regulate naval encounters between anti-submarine and supporting assets, China should work directly with regional countries too. If Beijing feels it is necessary to set up and protect SSBN bastions in the South China Sea, it should try to reach common understandings with other regional actors about which specific activities aimed at achieving this goal are permitted. Beijing should formally renounce overly aggressive pro-SSBN activities that clearly jeopardize the legitimate security interests of others.

More importantly, any Chinese efforts to be more transparent about its development and deployment plans for its SSBNs could help reassure other regional actors. As China’s SSBN capabilities continue to grow, it will be beneficial for Beijing to regularly reaffirm its unconditional NFU nuclear weapons policy and to categorically renounce any plans to use nuclear weapons for any mission other than nuclear counterattack. Such reassurances would reduce the potential interest of regional countries in conducting aggressive ASW operations against Chinese SSBNs or in joining U.S. efforts to do so.

Beyond that, China should consider signing and ratifying the protocol to the Southeast Asia Nuclear-Weapon-Free Zone Treaty sooner rather than later. The protocol would require the five nuclear weapon states recognized by the NPT to respect the nuclear weapon–free status of Southeast Asia and provide negative security assurances to its members. A close reading of the provisions of the treaty and its protocol shows that these provisions would not necessarily undermine China’s right to operate SSBNs in areas covered by the treaty, regardless of whether existing territorial disputes in the region are resolved.15 ASEAN members have repeatedly called on nuclear weapon states to sign and ratify the protocol. If China were to do so soon, that would further demonstrate Beijing’s intention not to threaten ASEAN countries with nuclear weapons and its commitment to work with ASEAN countries to advance the common goal of peace and stability in Southeast Asia.

Main Policy Takeaways

  • China should aim to reassure regional states that it is not pursuing a comprehensive sea-control capability in the region but is instead simply aiming to achieve the limited and defensive goal of protecting its sea-based nuclear deterrent vis-à-vis the United States.
  • Countries in the region should work toward reaching some common understandings on what specific Chinese military activities are legitimate for protecting SSBNs.
  • China could be more transparent about the development and deployment plans for its SSBNs operating in the South China Sea.
  • Beijing should reaffirm its unconditional NFU policy on a regular basis and categorically renounce any plans to use nuclear weapons in any missions other than nuclear counterattack, including by explicitly ruling out nuclear attacks on South Korea or Japan.
  • China should consider signing and ratifying the Protocol to the Southeast Asia Nuclear-Weapon-Free Zone Treaty sooner rather than later.

Unilateral Measures for China to Consider

In addition to cooperative or reciprocal confidence-building measures, there are unilateral steps that China could take to ensure its SSBNs fulfill their strategic objective of enhancing nuclear deterrence without causing unnecessary instability or undermining China’s own interests. These unilateral policy recommendations pertain to the ways China builds and employs its SSBNs and therefore can be taken regardless of whether the aforementioned reciprocal measures materialize.

There are unilateral steps that China could take to ensure its SSBNs fulfill their strategic objective of enhancing nuclear deterrence without causing unnecessary instability or undermining China’s own interests.

Adopt a Temperate Patrol Strategy:

There is no need for Beijing to maintain a continuous-at-sea deterrence posture during peacetime, because there is no realistic possibility of China being attacked, without warning, by a sudden nuclear strike. Moreover, China faces no non-nuclear existential threats, except over Taiwan, and even in that case Beijing’s NFU pledge would still apply.16 Additionally—unlike the UK, which does maintain a continuous-at-sea deterrent—China has other elements in its nuclear arsenal, including land-based nuclear missiles (which traditionally have constituted the backbone of its nuclear deterrence capabilities) as well as improving airborne nuclear capabilities.

As a peacetime alternative to continuous-at-sea deterrence, China could conduct occasional patrols to ensure that the crews remain proficient and that the submarines stay in good working order. If a crisis emerged, Beijing could send its SSBNs to sea to conduct patrols. A crisis, especially one serious enough to prompt China to alert its SSBN forces, would almost certainly take time to build up. If Beijing can keep its crews well trained and its submarines well maintained, it would always have the option of flushing its SSBNs at the first sign of a potential military crisis.

The most common counterargument to this posture is that, if a country does not maintain continuous-at-sea deterrence, sending SSBNs to sea during a crisis could be misunderstood by an adversary as an act of escalation. This is a reasonable concern, but there are ways to mitigate the problem. For instance, China could conduct its peacetime patrols irregularly without any discernable deployment pattern. That way, an adversary would not be able to determine whether a patrol during a crisis was routine or a response to the situation. Moreover, SSBN patrols would only be escalatory if they were detected, and it is uncertain if potential adversaries can always monitor the movements of China’s SSBNs. To increase the likelihood that the United States would not detect SSBN movements in a crisis and so mitigate the problem of unintended escalation, China could adopt a wide range of concealment and deception tactics, if it does not do so already. The Hainan submarine base, for example, is reported to include underground facilities built inside the island’s hills and is thought to have underwater exits for submarines to leave the facilities without being detected.17

Conducting strategic patrols less frequently would have other additional benefits, including conserving nuclear fuel for submarine reactors. This is probably not a trivial consideration given that refueling submarine reactors is a time-consuming, expensive process. Submarines have no military utility while they are being refueled, a process that typically involves cutting the submarine open. The U.S. Ohio-class SSBN, for example, requires a four-year, mid-life overhaul, including a two-year refueling period.18 (Future U.S. Columbia-class SSBNs will be equipped with a life-of-the-ship core, but it seems unlikely that China’s 094-class submarines have this capability.)

Main Policy Takeaways

  • China does not need to maintain a continuous-at-sea deterrence posture during peacetime.
  • Beijing should conduct its peacetime patrols on an irregular basis without showing any discernable pattern of deployments.
  • China can take a wide range of concealment and deception tactics to mitigate the problem of unintended escalation when deploying SSBNs during a crisis.

Keep SSBNs on a Moderate Alert Status:

Aside from patrol frequency, China does not need to keep its SSBN forces on high alert during peacetime. On peacetime patrols, Beijing could maintain deterrence without always arming its SLBMs with nuclear warheads or even without having its SSBNs always carry SLBMs. As long as China did not reveal whether its SSBNs carried missiles, or whether the missiles carried warheads, potential enemies would have to assume that they did. In practice, therefore, China could occasionally choose to arm its patrolling SSBNs with missiles and warheads depending on the situation. This approach would not undermine the credibility of China’s sea-based nuclear deterrent during peacetime, but it could reduce the dangers associated with always carrying real warheads and the consequences of incidents at sea involving SSBNs. If military tensions built up, a prospect that generally takes time to unfold, China could start arming all the SSBNs it sent out on patrol.

One potential concern is that such a strategy could increase inadvertent escalation risks. This strategy would rely on China’s ability to successfully conceal which SSBNs were armed—concealment efforts that might not always succeed. Occasionally, an adversary might detect missiles and warheads being loaded into submarines in port. If this happened during a security crisis, the adversary might misinterpret these actions as Chinese preparations for nuclear use, whereas, in fact, China would simply be taking precautions. Once again, though, this risk could be mitigated by dedicated efforts—such as the use of reported underground submarine facilities—to securely hide such activities from outside observers.

Additionally, China’s leaders need to decide what an SSBN should do if communications were lost during a serious crisis. If Chinese military plans require that SLBMs be targeted at cities and industrial hubs, then there would be no need for an SSBN to launch its missiles in haste if communications broke down. Such targets are stationary, and it would make sense for the SSBN in question to wait until communications were restored before taking action. That said, it is possible that, during a communications blackout, a submarine could face an imminent and serious threat of enemy attack.

Chinese leaders would need to decide whether to pre-delegate launch authority to SSBN commanders in such a scenario and, if so, how. To reduce the need to pre-delegate and to narrow the situations in which SSBN commanders would be granted launch authority, it is crucial for China to develop high confidence in the survivability of its top leadership and the C3 systems that its nuclear forces, including its SSBNs, rely on. Attaining such confidence will require Beijing to develop a highly secure, reliable, and redundant C3 system. China already seems to be on the path to doing so, by utilizing SLF radio communications, conducting research into ELF radio communications, developing an airborne C3 system, and exploring satellite communication technologies, among other measures.19

Improving the C3 system for Chinese SSBNs will be a time-consuming and incremental process, and setbacks are likely. As a point of comparison, in the mid-1990s, the U.S. Navy reportedly discovered a serious new threat to an SSBN communications system and took drastic steps to redesign launch procedures for its SSBN crews.20 In a similar way, China will inevitably go through a lengthy period of learning and adaptation as it seeks to develop an effective C3 system for its SSBNs. In the meantime, the United States and other relevant countries could help reduce Beijing’s incentives to pre-delegate launch authority by pledging to not deliberately disrupt or interfere with China’s C3 system. Such a commitment would incentivize China to prioritize efforts to prevent the unauthorized launch of sea-based nuclear weapons.

Main Policy Takeaways

  • China does not need to keep its SSBN forces on high alert during peacetime. It could maintain deterrence without always arming its SLBMs with nuclear warheads or even without having its SSBNs always carry SLBMs on peacetime patrols.
  • Beijing should prioritize ensuring against the unauthorized launch of sea-based nuclear weapons. A robust C3 system is very important for achieving this goal and for avoiding the need to pre-delegate launch authority.

Avoid Nuclear and Conventional Entanglement:

China can further limit crisis instability by delineating between its nuclear and conventional naval assets as clearly as possible. Although it is common for senior PLA naval experts to envision future SSBNs as integrated platforms that deploy both nuclear and conventional weapons, Chinese SSBNs should remain exclusively dedicated to the nuclear mission. The risk of inadvertent escalation from deploying both nuclear and conventional weapons on SSBNs is too high and would outweigh any potential military gains. Moreover, the seemingly widespread view among some Chinese experts that future SSBNs are trending toward becoming platforms that host nuclear weapons, conventional weapons, and even missile defense interceptors is based on a misreading of foreign national security plans.

Contrary to the views of these Chinese experts, the United States is somewhat aware of the problems associated with nuclear-conventional entanglement and has, in recent years, taken measures to avoid mixing nuclear and conventional weapons on the same platforms. In the mid-2000s, the U.S. Congress rejected funding for the Conventional Trident Modification program (which sought to replace nuclear warheads with conventional ones on some Trident D5 missiles).21 This ambition was abandoned out of concerns that potential adversaries might mistake the launch of a conventionally armed Trident for a nuclear-armed missile, leading to inadvertent escalation. Moreover, while the U.S. Navy does deploy conventional cruise missiles on four Ohio-class submarines, those vessels have been converted to designated cruise missile submarines and no longer carry any nuclear weapons.

It is in Beijing’s interest to learn these same lessons. If China is concerned that SSBNs have limited military utility, it should limit the number that it builds. Putting conventional missiles on SSBNs to make them purportedly well-rounded platforms (or, for that matter, arming SSNs with nuclear cruise missiles) may be cost effective, but it is also strategically risky.

An even more pressing issue is the likely entanglement of nuclear and conventional C3 systems for naval forces. Despite the lack of definitive evidence, it is probable that current Chinese SSBNs share some command, control, and communications systems with non-nuclear forces. For instance, some radio broadcast systems may be used for communicating with both SSBNs and attack submarines. If such dual-use C3 systems were attacked in a conventional conflict, the risk of misinterpretation would be real. Ideally, countries would make their C3 systems for SSBNs completely separate from their C3 infrastructure for other naval platforms, including attack submarines.

In practice, however, doing so might be technically, logistically, and financially challenging. A more viable alternative for China might be to deploy one or more SSBN-dedicated C3 systems, alongside other dual-use C3 systems shared by SSBNs and some general-purpose forces. Such dual-use capabilities could increase redundancy in useful ways. Furthermore, a dedicated C3 system could reduce Chinese concerns about losing effective control over its SSBNs, in the event that some dual-use systems were attacked in a conventional conflict.

More generally, China should seek to understand the specific risks resulting from C3 entanglement and take them into consideration when formulating procurement policies and operational plans. At present, awareness and appreciation of such risks—especially among senior Chinese military officials and political decisionmakers—is low. China should conduct more internal research to understand and address these dynamics.

Main Policy Takeaways

  • China should recognize that the escalation risks associated with arming submarines with both nuclear and conventional weapons would outweigh any increase in military utility, and it should categorically reject this course of action.
  • The Chinese expert community should closely examine the practices of other major nuclear powers to avoid concluding incorrectly that arming submarines with both nuclear and conventional weapons represents an international trend.
  • China should conduct internal research to better understand the risks posed by dual-use C3 systems and should ensure that such risks inform procurement policy and operational planning. Beijing should consider deploying a dedicated SSBN C3 system that is separate from the C3 systems for general-purpose forces.

Keep the SSBN Force Lean and Effective:

Beyond these concerns about crisis instability, the ultimate size of China’s SSBN fleet has serious long-term implications for arms race stability. Beijing’s image as a responsible nuclear power can be best maintained by building a modest SSBN force, in line with the principle of maintaining a lean and effective nuclear force that has guided the development of China’s force posture for decades.

Given the very limited number of ICBMs that China currently possesses, each new SSBN represents a substantial addition to China’s strategic nuclear capabilities. Such additions could contribute significantly to potential enemies’ threat perceptions—particularly if Beijing’s SLBMs are, or will be, deployed with multiple warheads. Moreover, if China continues to improve the accuracy of its SLBMs, the first-strike potential of a relatively large SSBN fleet could appear increasingly threatening to China’s nuclear rivals, particularly India. The result could be additional pressure on New Delhi to build a larger nuclear arsenal and to reconsider its own existing NFU policy, a development that would have profound ramifications for crisis stability.

Strategically speaking, the optimal size of a country’s SSBN fleet should depend on its specific operational strategy. Given its objective of ensuring the overall credibility of its nuclear retaliatory capabilities, China may not need to build a large-scale SSBN fleet. The experts who have proposed fleets of at least eight SSBNs have not elaborated on what deployment strategies would best serve China’s military objectives.

If China does not adopt continuous-at-sea deterrence, the four or five SSBNs that it has reportedly already built should be more than adequate for a credible sea-based nuclear deterrent. In fact, given the British and French examples, China may even be able to adopt a continuous-at-sea deterrence posture with its existing fleet—though this claim is disputed by some Chinese experts. Financially, too, China has an incentive to keep its fleet as small as possible, consistent with operational requirements—not least because the cost of operating each SSBN may be greater for China than the equivalent cost to the United States. This is at least partially because U.S. SSBNs rely primarily on stealth for survival and do not need much additional protection (if any) from general-purpose forces. By contrast, current Chinese SSBNs are noisy enough to need greater protection. Especially if Beijing adopts a bastion deployment strategy, it will need to devote significant resources to protecting its SSBNs with general-purpose forces.

Instead of building a large, expensive SSBN fleet when the country faces no serious existential threat, China should consider a smarter, less expensive alternative that would be more conducive for maintaining strategic stability. China could keep its SSBN fleet relatively small for the time being. It could focus its resources on training extra sets of SSBN crews and maintaining a responsive ship-building infrastructure. If the Asia Pacific’s geostrategic environment changed radically and China needed more SSBNs to deal with a new threat, the country would have the industrial capability to quickly mass produce a few more SSBNs within several years. The extra sets of crews trained during peacetime would be ready to operate these submarines as soon as they were produced. This hedging strategy deserves serious consideration because any fundamental change in China’s geostrategic environment that would require Beijing to enlarge its SSBN fleet would likely take a few years to develop.

If China does choose to keep its SSBN fleet small, it would be in the country’s interest to make this decision clear to international observers. Beijing’s existing policy of not providing authoritative information about plans for developing China’s SSBN fleet leaves room for wild speculation. In August 2016, for instance, a local government-run television network in the coastal city of Huludao broadcasted a story about a top official from the Bohai Shipbuilding Heavy Industry Company inspecting a construction site for a new assembly line. (The story included pictures from inside the facility.)22 The company’s shipyard at Huludao has been the primary construction site for Chinese nuclear submarines, both SSBNs and SSNs. Consequently, foreign and Hong Kong–based observers speculated that China was significantly expanding its submarine building capacity to facilitate a major expansion of its SSBN and SSN fleets.23 This conjecture was subsequently picked up by Chinese media outlets with some official standing, including Cankao Xiaoxi, the Global Times, the People’s Daily website, and a publication managed by the National Development and Reform Commission.24

More in-depth research suggests that this speculation may be based on a false premise. A careful analysis of the foundation of the new assembly hall suggests that this facility is most likely for building high-value commercial ships.25 To discourage exaggerated foreign threat perceptions, it would behoove China to break with tradition and provide some general but authoritative information about its long-term plans for SSBN development, to the extent that sensitive military information would not be compromised.

In addition to maintaining a moderately sized SSBN fleet, Beijing should limit how many SLBMs it puts on each submarine. As technology and China’s geostrategic environment have evolved, the need to deploy many SLBMs on each SSBN has generally declined. In the case of the United States, Ohio-class SSBNs used to have twenty-four operational SLBM tubes, but Washington decided to reduce that number to twenty so as to fulfill its New Strategic Arms Reduction Treaty (New START) obligations.26 This process was completed in July 2017.27 Moreover, each next-generation Columbia-class SSBN will have only sixteen missile tubes.28 Similarly, the UK government announced in its 2010 Strategic Defense and Security Review that it would “reduce the number of operational launch tubes on [UK] submarines from 12 to eight,” a policy that will apply to both existing Vanguard-class and next-generation Dreadnought-class SSBNs.29

By contrast, some Chinese commentators argue that China should greatly increase the number of SLBMs on each SSBN, from twelve on its 094-class submarines to as many as twenty-four for the next-generation SSBN.30 Their thinking is that putting more SLBMs on each SSBN would improve cost-effectiveness, but this perspective seems out of touch with both Chinese strategic requirements and international trends. Furthermore, increasing the number of SLBMs on an SSBN reduces the submarine’s maximum speed, which could undermine its ability to escape from danger and transit quickly to a patrol area during a crisis.31 By contrast, an SSBN with fewer SLBM launchers would be smaller, lighter, more flexible, and, thus, more survivable.32 The comparative loss of any given SSBN would be less significant, which would enhance crisis stability.

Main Policy Takeaways

  • China can obtain a credible sea-based nuclear deterrent without developing a large SSBN fleet.
  • China can maintain its image as a responsible nuclear power by keeping its SSBN force lean. To bolster this image, Beijing should proactively provide authoritative information about its SSBN development plans.
  • While keeping its SSBN fleet relatively small for the time being, China could hedge against future uncertainties over its security environment by focusing resources on training extra sets of SSBN crews and maintaining a responsive ship-building infrastructure.
  • China should not increase the number of SLBMs on each submarine.

These policy recommendations constitute a starting point for China, the United States, and U.S. allies to responsibly manage the risks posed to strategic stability by the growth of China’s SSBN fleet and U.S. ASW capabilities. While these suggestions will not completely eliminate the potential risks of crisis instability or an arms race, they are necessary steps to maintain stable U.S.-China nuclear relations and to preserve peace, stability, and security in the Asia Pacific region.

Notes

1 James A. Hayes, “SSBN Survivability: A Time for Confidence-Building Measures?,” Naval Postgraduate School, 1982; and James J. Tritten, “A New Case for Naval Arms Control,” Naval Postgraduate School, December 1992.

2 Posen, Inadvertent Escalation: Conventional War and Nuclear Risks, 197­–218.

3 Wu Riqiang, “How China Practices and Thinks About Nuclear Transparency,” in Understanding Chinese Nuclear Thinking, ed. Li Bin and Tong Zhao (Washington, DC: Carnegie Endowment for International Peace, October 2016).

4 Richard D. Fisher Jr., “China and START,” Washington Times, September 20, 2010.

5 Kris Osborn, “How the U.S. Navy Plans to Take on Russia and China’s Deadly Submarines,” National Interest, April 4, 2017.

6 Eugene Miasnikov, “The Future of Russia’s Strategic Nuclear Forces: Discussions and Arguments,” Moscow Institute of Physics and Technology Center for Arms Control, Energy, and Environmental Studies, 1995.

7 Posen, Inadvertent Escalation: Conventional War and Nuclear Risks, 129–158.

8 Zhang Yang (张杨), Zhang Fang (张芳), and Bian Yong (卞勇), “Application of Laser Communication in Submarine Communication” [激光通信及其在潜艇通信中的应用], Optical Communication Technology (光通信技术) 30, no. 7 (2006); and “China’s Super Low Frequency Deep Water Submarine Communication System Comes Online” [我国建成超低频对潜深水通信系统].

9 Department of the Navy and the National Security Agency, “Ep-3e Collision: Cryptologic Damage Assessment and Incident Review—Final Report,” Department of the Navy and the National Security Agency, July 2001, https://assets.documentcloud.org/documents/3546567/10th-Anniversary-Edition-EP-3-Damage-Assessment.pdf.

10 “FT-2000 Surface to Air Missile” [Ft(飞腾)-2000], China Institute of International and Strategic Studies, September 14, 2010, http://arsenal.chinaiiss.com/html/20109/14/a2aab5.html. This source has since been taken down.

11 “Memorandum of Understanding on the Rules of Behavior for Safety of Air and Maritime Encounters Between the Department of Defense of the United States of America and the Ministry of National Defense of the People's Republic of China,” http://archive.defense.gov/pubs/141112_MemorandumOfUnderstandingRegardingRules.pdf; “Supplement to the Memorandum of Understanding on the Rules of Behavior for Safety of Air and Maritime Encounters Between the Department of Defense of the United States of America and the Ministry of National Defense of the People's Republic of China.”

12 Ibid.

13 Conversation with a senior official of the U.S. Pacific Fleet, August 2016.

14 Yan Yan (闫岩), “Analysis on American Unmanned Underwater Vehicle Sovereign Immunity” [关于美无人潜航器豁免权问题评析], National Institute for South China Sea Studies (中国南海研究院), December 2016.

15 Tong Zhao, “Nuclear Weapon States and the Southeast Asia Nuclear-Weapon-Free Zone,” in Asia Pacific Leadership Network for Nuclear Non-Proliferation and Disarmament Policy Brief no. 28, February 2017.

16 “China Says It Will Not Use Nuclear Weapons against Taiwan,” New York Times, September 3, 1999, http://www.nytimes.com/1999/09/03/world/china-says-it-will-not-use-nuclear-weapons-against-taiwan.html.

17 Bell, “The Impact of the Type 094 Ballistic Missile Submarine on China’s Nuclear Policy.”

18 O’Rourke, “Navy Columbia Class (Ohio Replacement) Ballistic Missile Submarine (Ssbn [X]) Program: Background and Issues for Congress.”

19 Wu, “Have China's Strategic Nuclear Submarines Started Operational Patrols?” [中国战略核潜艇开始战备巡航了吗?]; “China’s Super Low Frequency Deep Water Submarine Communication System Comes Online” [我国建成超低频对潜深水通信系统].

20 Bruce G. Blair, “Why Our Nuclear Weapons Can Be Hacked,” New York Times, March 14, 2017.

21 Amy F. Woolf, “Conventional Warheads for Long-Range Ballistic Missiles: Background and Issues for Congress,” Congressional Research Service, 2009.

22 Fang Zhou (方舟) and Xu Chenchen (徐晨晨), “Chairman Li Tianbao Visited Construction Site of New Assembly Line Project” [李天宝董事长到新型总装生产线建设项目现场调研], Huludao Broadcast and TV Network (葫芦岛广播电视网), http://www.hldbtv.com/ProgramsData/Item_96857.aspx.

23 Jeffrey Lin and P.W. Singer, “China Is Building the World’s Largest Nuclear Submarine Facility,” Popular Science, April 19, 2017; and “New Nuclear Submarine Assembly Line Just Built” [新核潛艇總裝生產線剛落成], Oriental Daily (东方日报), August 29, 2016.

24 Zhang, “China’s Rarely Seen Nuclear Submarine Factory Revealed; Hong Kong Media: Can Built 5-6 Nuclear Submarines Simultaneously” [中国核潜艇工厂罕见曝光 港媒:可同时建造5至6艘核潜艇]; Qiu Yue (邱越) and Yan Jiaqi (闫嘉琪), “Hong Kong Media: New Nuclear Submarine Production Line Built in China - 096 Class About to Debut” [港媒称中国核潜艇新生产线落成 096型呼之欲出], People.cn (人民网), August 30, 2016; and “China Just Built Super Steel Structured Assembly Facility for Mass Production of Nuclear Submarines” [中国刚刚建成超级钢结构车间核潜艇批量生产], in China Strategic Emerging Industry (中国战略新兴产业), National Development and Reform Commission (国家发展改革委员会), February 06, 2017.

25 Carlson, “Why Everyone Is Wrong About China’s Next-Gen Submarines.”

26 “The New Start Treaty—Maintaining a Strong Nuclear Deterrent,” Air Force Magazine, May 20, 2010, http://www.airforcemag.com/SiteCollectionDocuments/Reports/2010/May%202010/Day18/NewSTARTsection1251factsheet.pdf.

27 Department of State Bureau of Arms Control, Verification, and Compliance, “Fact Sheet: New Start Treaty Aggregate Numbers of Strategic Offensive Arms,” Department of State Bureau of Arms Control, Verification, and Compliance, July 1, 2017.

28 O’Rourke, “Navy Columbia Class (Ohio Replacement) Ballistic Missile Submarine (Ssbn [X]) Program: Background and Issues for Congress.”

29 Claire Mills and Noel Dempsey, “Replacing the UK’s Nuclear Deterrent: Progress of the Dreadnought Class,” in House of Commons Library Briefing Paper Number 8010 June 19, 2017; and UK Prime Minister’s Office, “Securing Britain in an Age of Uncertainty: The Strategic Defence and Security Review,” October 2010, https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/62482/strategic-defence-security-review.pdf.

30 “Preliminary Analysis on Why China Has Not Established a Missile Nuclear Submarine Operational Patrol Mechanism” [浅谈中国为何从未建立过导弹核潜艇战备巡航制].

31 Lan, Dong, and Wen, “Divergent Views Over Strategic Nuclear Submarine Development” [战略核潜艇发展分歧].

32 Wu Kai (吴锴), “Design Doctrine of Strategic Nuclear Submarines: An Interview With Huang Xuhua - Academician of China’s Academy of Engineering” [战略核潜艇的设计思想——访中国工程院黄旭华院士], Ordnance Knowledge (兵器知识), no. 4 (2000).