This piece is part of a compilation bringing together Regional Voices on the Challenges of Nuclear Deterrence Stability in Southern Asia.

Introduction

China is investing heavily in its nuclear ballistic missile submarine (SSBN) capability. Western analysts point out that China’s first-generation SSBN, the 092-class, yielded only one submarine, which never conducted any patrols.1 But in a few short years, China has already built and deployed four second-generation SSBNs, the 094-class, according to the Pentagon’s annual report to Congress in 2015.2 The same report predicts that “up to five [094-class submarines] may enter service before China begins developing and fielding its next-generation SSBN, the Type 096, over the coming decade.” Some American officials believe the size of China’s 094 SSBN fleet could grow larger. In April 2015, the then–commander of the U.S. Pacific Command, Admiral Samuel Locklear, testified to Congress that “China now has three operational JIN-class ballistic missile submarines (Type 094), and up to five more may enter service by the end of the decade.”3 By expecting “five more” 094 submarines to be built, he was predicting that China may have a fleet of up to eight 094-class SSBNs by 2020. But beyond just building a large second-generation SSBN fleet, China is also having them conduct patrols, which it never did with the 092-class. According to the most recent report from the U.S. Defense Department, China’s nuclear ballistic missile submarines may start to conduct patrols in 2016.4 This, if true, would represent a major milestone in the development of China’s strategic nuclear submarine capability, which could raise alert and cause reactions in the Asia-Pacific region.

This study first discusses China’s motivations for developing and deploying sea-based nuclear weapons. It draws on primary Chinese literature to analyze how this new capability fits into China’s overall nuclear strategy. By reviewing the technical and policy constraints of China’s SSBN operation, the second section examines possible deployment strategies for China and potential trade-offs among these options. Finally, a discussion of the possible implications of the deployment of Chinese SSBNs for China’s nuclear posture highlights potential challenges that China will face in ensuring the survivability of its SSBNs in the future and hence the efficacy of its sea-based deterrent. Together, these sections show that China’s SSBN will contribute to reinforcing the credibility of the country’s nuclear second-strike capability, but is not intended to serve any role beyond minimum nuclear deterrence. However, the relatively high noise level of the 094-class SSBNs and the less-than-ideal maritime environment surrounding China constrains operational options for the country’s current SSBN fleet. China has a choice to make to ensure that its sea-based nuclear capability can be a helpful addition to its existing nuclear deterrent without destabilizing regional security. Other regional players, including the United States, also have a role to play to avoid undermining existing regional stability at the nuclear and conventional levels.

Chinese Motivations for Obtaining Sea-Based Nuclear Weapons

Motivations behind Historical Development

The history of China’s nuclear development reveals that its sea-based nuclear weapons program was very much motivated by similar programs undertaken by other major nuclear powers. The top Chinese leadership decided to start developing the country’s sea-based nuclear weapons capability in 1958,5 six years before China conducted its first nuclear test in 1964. This decision came four years after the United States launched its first nuclear submarine, the USS Nautilus, and only one year after the Soviet Union launched its first nuclear submarine, Leninsky Komsomol. Between 1954 and 1958, the United States launched multiple nuclear submarines. At the same time, the Soviets, the British, and the French were all researching how to build nuclear submarines or were already deploying them. News about such developments in these countries drew attention from the Chinese leadership.6 In June 1958, Marshal Nie Rongzhen, who was in charge of China’s defense industry, gathered the country’s top military and defense industry leaders in a Defense Technology Committee meeting to discuss the need for China to have its own nuclear submarine. They reached the conclusion that “China needs to develop nuclear submarines that can carry missiles” to “counter nuclear monopoly.”7 After this meeting, Nie submitted a “Report on Starting the Development of Missile Atomic Submarine” to the State Council and Chinese Communist Party Central Committee, and it was approved by top leaders, including Mao Zedong, Zhou Enlai, Deng Xiaoping, and Peng Dehuai.8 At that time, the People’s Republic of China was only seven years old and had just started preliminary research on atomic power generation and conventional submarine technology. Because China’s poorly equipped military was in dire need of even the most basic military hardware, highly complex weapon systems like missile nuclear submarines were likely superfluous and not needed immediately. That China continued to develop the program regardless of military necessity suggests that its leadership was driven by a desire to follow the trend of military development in the world’s other major powers.

National prestige also played an important role in driving early Chinese interest in nuclear missile submarines. When Mao Zedong turned to Nikita Khrushchev in 1959 for technological assistance in developing the nuclear submarine, he was told that “the technology is too complicated for China to master.” This comment insulted Mao and his Chinese scientists, prompting him to take a now well-known vow: “We will build our nuclear submarines, even if it takes 10,000 years!”9 The Chinese scientists also called the nuclear submarines they built the “win-honor boat” that “won honor for the nation and for Chairman Mao.”10

A broader analysis of Chinese military development in the 1960s and 1970s confirms that there was not much real, practical military urgency to develop the SSBN. For at least three decades, nuclear submarine development was a secondary priority, compared with land-based missiles and other military programs. When the defense budget was tight in the early 1960s, the nuclear submarine program was discontinued until 1966. Until the mid-1990s, the program received only moderate political attention and financial support.11

Current Security Motivations

In recent decades, however, the SSBN program has been a higher priority because of its potential to play a critical role in strengthening China’s nuclear deterrent. Chinese experts point to a number of practical reasons why a robust sea-based nuclear capability is becoming increasingly important for maintaining a credible nuclear deterrent.

First, in the long run, Chinese experts generally believe that a sea-based nuclear capability is more survivable than land-based systems. Admiral Liu Huaqing, who is hailed as the “father of the modern Chinese Navy” and served as vice chairman of the Central Military Commission from 1989 to 1998, stated that “fewer than ten percent of China’s land-based missiles would survive a large-scale nuclear first strike; less vulnerable SLBMs would preserve our nuclear counterattack capabilities.”12 China has made impressive progress in modernizing its land-based nuclear missiles, including improving the accuracy, mobility, and responsiveness of road-mobile missile vehicles; but there is still concern—in some cases, even more concern than before—among Chinese experts about the survivability of land-based systems. In particular, experts worry that growing U.S. missile defense, conventional precision strike, and space-based surveillance capability together allow for sophisticated preemptive attacks that pose significant threat to China’s land-based nuclear forces.13

Chinese strategists view sea-based nuclear weapons as comparatively less vulnerable. This perception of high survivability comes from several Chinese assumptions about SSBNs. First, SSBNs are highly stealthy.14 Detecting and tracking SSBNs requires an enemy to invest tremendous military resources.15 For this reason, preemptively destroying SSBNs is “more difficult than destroying [a] land-mobile launch system,” according to Tao Chunbo.16 Second, SSBNs are highly mobile and can considerably “expand the combat area” by patrolling in open oceans, and therefore can “increase the (geographical) surprise” of an attack, according to Yang Lianxin.17 Third, submarine-launched ballistic missiles (SLBMs) have a much better chance of defeating an enemy’s missile defense capabilities. This is because SSBNs can sail close to an enemy’s territory to launch missiles, leaving less time for the enemy to employ defensive measures before the missiles land.18 Also, if sailing in the Southern Pacific, Chinese SSBNs will be able to launch missiles along azimuths outside current American missile defense coverage.19The 2013 edition of the Science of Military Strategy—an important military textbook written by a group of prominent military scholars and published by the Chinese Academy of Military Sciences—points out that having the capability to penetrate U.S. missile defenses is a major motivation for China’s strategic nuclear submarine program: “Faced with the objective situation of the United States and countries on China’s periphery actively developing missile defenses, developing China’s sea-based deterrent force is significant for the reliability, credibility, and effectiveness of protecting China’s nuclear deterrent and counterstrike capabilities.”20

Chinese strategists also respond in part to international trends in nuclear submarine development. They take note that all other nuclear weapons states have elevated the role of sea-based nuclear weapons in their nuclear programs, and they conclude that “from the global perspective, the proportion of sea-based nuclear capability in national nuclear deterrent system[s] will continue to rise.”21 For example, current U.S. sea-based nuclear weapons now constitute 60 percent of all American nuclear deterrent capability. This proportion is expected to rise to 70 percent by 2018. Chinese analysts also expect Russia to increase its reliance on SLBMs as a proportion of its arsenal, from 23 percent in 2010 to 57 percent in 2020.22 Crucially, Chinese strategists see that this policy development is occurring across all “mid-level nuclear weapons states,” a group that consists of France and the United Kingdom, and to which they believe China also belongs. They point out that “establishing a minimum underwater nuclear capability is a common understanding among mid-level nuclear weapons states,” which further reinforces the belief that “nuclear submarines armed with strategic nuclear missiles are the most ideal type of nuclear retaliation capability.”23 SSBNs are appropriate for a country of China’s position.

Foreign government and independent experts doubt whether China can actually realize the full benefits of SSBN and SLBM technology, given that Chinese technologies are still far from perfect. According to a 2009 assessment by the U.S. Office of Naval Intelligence, China’s second-generation 094 SSBN is noisier than the 1970s-vintage Russian Delta III SSBN.24 One Chinese analyst, using open-source research, estimates that at low frequency (100 hertz), the noise level of the 094 SSBN is about 140 decibels—much noisier than existing nuclear submarines in the United States, Russia, France, and the United Kingdom.25 If this estimation is correct, the 094 SSBN would still belong to the category of “noisy submarines.” In comparison, the noise levels of “quiet submarines” and “very quiet submarines” are generally around 120 dB and 100 dB respectively (at a range between 5 and 200 hertz).26 The Russian Delta IV SSBN, for example, is usually believed to be a “quiet submarine,” and the American Ohio-class SSBN may be close to being “very quiet.” It is worth noting that when China was building its first-generation nuclear submarines, its official policy was to first build a prototype boat as quickly as possible and then to work on improvements later in the production of future boats.27 The Chinese leadership may also be adopting the same strategy for second-generation submarines, which means that while the first boat of the 094-class might have been a “noisy submarine,” subsequent boats may perform better. The fact that China has been mass producing the 094 SSBNs—with four of a planned five to eight already completed—also indicates that the Chinese leadership is relatively satisfied with its overall performance.

That said, some basic aspects of the 094’s design seriously limit its potential to become a genuinely quiet submarine. Its large missile compartment, the numerous free-flood openings in its casing, and its skewed propeller, among other basic design features, make it very difficult to dramatically reduce its noise level.28 Compared with Russian and Western SSBNs, for which quietness was only achieved when noise reduction was a fundamental driving parameter of their design and construction, Chinese SSBNs still have some way to go to obtain the necessary experience and improve the technology. This considerably constrains China’s current SSBN operations and makes SSBNs a less effective deterrence asset. Chinese strategists do acknowledge these limitations. When discussing the role of China’s first-generation nuclear submarines, they emphasize that the main objective was to “fill in the blanks”—that is, to solve the issue of “have versus have not” before focusing on technological sophistication. Also, beyond their combat functions, nuclear submarines serve as “schools and labs” for the Chinese Navy, in the sense that they help China “gain the experience operating large and complex equipment” and “train next-generation sailors and technicians.”29 Therefore, even though China’s second-generation SSBNs are beginning to take on deterrence patrol missions, a major part of their responsibility may still be to provide their crews with operational experience. As one Chinese expert states, it is most important for China to use its current SSBNs to “serve as a platform for testing technology and training crews, and to accumulate experience on ballistic missile submarine operations.”30

Some independent Chinese analysts and commentators recognize the limit of SSBN’s value for China, when compared with other military assets. For instance, they point out that the role that an SSBN can play is comparatively narrow; SSBNs are only for launching strategic nuclear counterstrikes after China is attacked by nuclear weapons, as is the case with Chinese nuclear weapons under the no-first-use policy. In a military crisis, SSBNs cannot help resolve regional maritime conflicts or conduct military missions, like escorting other ships; they cannot conduct antisubmarine operations; and they cannot take on counterpiracy, counterterrorism, or refugee and expatriate rescue missions. In peacetime, they cannot contribute to military diplomacy through overseas visits.31 As a result, from the perspective of military utility, some scholars argue that China should focus on developing nuclear-powered attack submarines rather than ballistic missile nuclear submarines.32 This view, however, is not mainstream in most public discussions.

Operating Posture

The operational strategy of China’s SSBN fleet is influenced by its threat perception, its military objective, and its operational capabilities. There is little doubt that China’s sea-based nuclear capability is primarily intended to address the perceived threat from the United States, which is also unquestionably the primary target of China’s overall nuclear deterrent. All Chinese discussions assume that China’s ultimate goal for its strategic nuclear submarine forces is to be able to launch nuclear retaliation that can reach the continental United States.33 Some foreign scholars suggest that Chinese SSBNs also have the capability to hold Indian homeland targets at risk and that China may be motivated to deter India from using its SSBN capability.34 They point out that when deployed in the South China Sea, a Chinese SSBN can easily launch strikes against India without sailing into the Indian Ocean.35 The Chinese literature, however, rarely implies an interest in using SSBNs as deterrence against India. Admittedly, China does not need to openly declare that its SSBNs are to deter India, if that is its intention; but there has been no indication that the deployment of SSBNs in the South China Sea is driven by a desire to deter India. In the long term, however, Chinese strategists are watching Indian efforts to close the two countries’ nuclear gap by extending the range and number of India’s strategic missiles and building more advanced SSBNs.36 If this trend continues, it is not totally improbable that China would want its SSBNs to play a role in deterring India as well; but at present, this does not appear to be a Chinese concern.

Some foreign scholars worry that the introduction of SSBNs to China’s existing nuclear forces may represent a shift of Chinese nuclear strategy from a minimum nuclear deterrent to a limited nuclear deterrent. According to Alastair Iain Johnston, if China pursues a strategy of minimum nuclear deterrence, it would only attempt to deter a first nuclear strike by threatening massive nuclear retaliations against soft targets like population centers, regardless of the size of the first strike or the specific context in which the first strike was conducted.37 However, if China seeks to achieve something more, perhaps by embracing plans to carry out limited nuclear retaliation with the purpose of managing escalation in nuclear conflicts, it would be going beyond a minimum nuclear deterrent and shifting to a limited nuclear deterrent strategy.38

Some Chinese scholars once suggested that China should develop a very limited nuclear war-fighting capability (not necessarily to be implemented by SSBNs) in order to be able to respond proportionally to an enemy’s small-scale nuclear first strike. Such scholars believe that it is in China’s interests to be able to launch small-scale nuclear retaliation against military targets, much like the American “flexible response” strategy.39 Such thought conforms to mainstream American nuclear thinking and is therefore easily understood by American experts. When such Chinese scholars began advocating a “flexible response” type of strategy, American experts took it as evidence that China was shifting from a strategy of minimum nuclear deterrence to one of limited nuclear deterrence. When American scholars discovered China’s development of SSBN capability, they saw it as a step by China to obtain a limited nuclear deterrent capability.40 Because China’s strategic nuclear submarines can sail close to enemy territory, and because their SLBMs take shorter time to arrive at targets than land-based intercontinental ballistic missiles (ICBMs), Western experts see this as a new tactical nuclear strike capability of China and argue that China’s SSBN capability can give its leadership broader nuclear options that “provide a platform capable of engaging in ‘nuclear war fighting.’”41

A closer look at the Chinese domestic discussion, however, paints a slightly different picture of the Chinese leadership’s intentions for SSBN employment. The view that China should develop a limited nuclear war-fighting capability to manage conflict escalation is clearly a minority view that is not heard very often in the Chinese scholarly or policy communities.42 The common view of senior Chinese experts is still that China intends to deter any nuclear first strike by threatening massive nuclear retaliation.43

The only real change is China’s confidence in its nuclear retaliation capability. For many decades, China possessed only a rudimentary nuclear capability with very low survivability. Until recently, some Western scholars thought that the United States has the capability to preemptively destroy all Chinese nuclear forces in a disarming first strike.44 Some Chinese strategists share this opinion, and they thus view the development of sea-based nuclear capabilities as essential to ensuring the absolute credibility of China’s overall nuclear deterrent. They believe the addition of an SSBN fleet can ultimately guarantee that China’s nuclear arsenal will be absolutely safe and survivable. Called “the Second Nuclear Force” by some Chinese analysts,45 the SSBN fleet is expected, first, to remove any doubt in the mind of potential adversaries about China’s retaliation capability and, second, to force the United States to unequivocally recognize that China and the United States have a relationship of mutual vulnerability.46 There has been little discussion about using SSBNs in limited nuclear conflicts or using SLBMs against military targets.

Internal discussions about the operational strategy for China’s SSBN fleet fall in line with its assigned role of strategic nuclear deterrence. Chinese discussions focus on two main deployment strategies. One is similar to the American approach, which is to have SSBNs conduct patrols in the open ocean. In this case, the SSBN primarily relies on its own stealth capabilities to transit to patrol areas in the open ocean and stay undetected during the patrol period. This approach requires that the submarine run quiet enough to avoid detection.47 The second strategy is similar to Soviet policy in the later years of its SSBN operation, when the Soviets deployed SSBNs in designated areas (that is, submarine bastions) in coastal water. This “bastion” strategy ensured that SSBNs received protection by other elements of the Soviet Navy, which made them more likely to survive, even in the face of advanced enemy antisubmarine warfare (ASW) capabilities.48

Chinese strategists are clearly very interested in the open ocean patrol strategy; many of them believe that it is the ultimate goal for China’s SSBN fleet.49 Open ocean patrols will relieve the Chinese Navy of the burden of creating submarine bastions, which are very resource intensive. These patrols also haves the benefit of increasing the chances of penetrating U.S. ballistic missile defenses.50 In addition, the existing Chinese SLBM, the JL-2, only has a range of 7,000 kilometers and thus cannot currently reach the continental United States from Chinese coastal water.51 If putting the continental United States within missile range is in fact a goal of the Chinese military, the Chinese leadership has a strong incentive to send SSBNs into the open ocean as soon as possible.

The downside of the open ocean patrol strategy is that it requires very quiet submarines. If a submarine safely arrives at its patrol area in the open ocean without being trailed, it can reduce its noise by patrolling at a very low speed and therefore minimize the risk of being detected. The more challenging part is the transit period from the port to the open ocean. During transit, the submarine needs to maintain a not-too-low speed in order to reach the patrol area in a reasonable time. This means that its noise will be relatively high, rendering it more vulnerable to enemy detection. Noise control is an especially important concern for the Chinese SSBN because its transit route from the South China Sea or Yellow Sea passes through the so-called First Island Chain via water channels that are adjacent to enemy-controlled territories.52 These channels are closely monitored by the ASW capabilities of the United States, Japan, Taiwan, and, often, the Philippines. The United States and Japan have been working together to upgrade the underwater sound surveillance system that the United States first deployed during the Cold War.53 All these factors make noisy Chinese SSBNs very easy to detect during their transit to the Western Pacific.

There are cases in which foreign countries have detected Chinese nuclear submarines in transit because of their noise. In 2004, a 091 class nuclear attack submarine was reportedly detected by Japanese, Taiwanese, and American ASW platforms when the submarine sailed from the Western Pacific back to China, passing by Japanese waters.54 Because of these incidents, Chinese strategists have been particularly emphatic about the importance of noise control.55 Besides working on manufacturing quieter submarines, China is also likely to employ alternative strategies to send its SSBNs safely into the Western Pacific. For instance, according to some independent Chinese analysts, China may use surface vessels to escort SSBN into the Western Pacific before the SSBN breaks loose from the fleet and starts independent patrols.56 Even though there is no confirmation that this tactic has been adopted by the Chinese Navy, China has been sending its naval surface ship fleets into the Western Pacific to conduct training missions more frequently in recent years.57

Given the noise level of the existing Chinese SSBNs, the bastion strategy seems to offer a better near-term solution. Chinese 094 SSBNs have been spotted by satellites at both the submarine base near Qingdao in Shandong Province and the newly built base near Sanya on Hainan Island.58Some Chinese experts speculate that it is possible that China may set up two submarine bastions, one near the Qingdao base in the Yellow Sea and the other near the Sanya base in the South China Sea.59 This is a reasonable assessment, given that the Yellow Sea and South China Sea are the only two bodies of coastal water that are not too shallow for SSBN operations. Of the two possible bastion locations, the South China Sea seems to have greater potential. The South China Sea’s average water depth is much greater than that of the Yellow Sea, and its water temperature and salinity are both more conducive to generating thermocline and pycnocline, features that affect sound propagation under water and complicate submarine detection. The South China Sea is thus a more feasible and attractive option.

The problem for deploying SSBNs in the South China Sea, however, is that the range of the existing Chinese SLBM, the JL-2, is not long enough to reach the continental United States from the South China Sea, according to the Pentagon’s estimate.60 Although the JL-2s may be able to strike overseas U.S. territories such as Guam and Hawaii, they have a reduced deterrent effect because they are not able to strike the continental United States. Furthermore, unlike the Soviet Union and Russia, which could set up submarine bastions in relatively isolated coastal waters such as in the Sea of Okhotsk and the Kara Sea, the South China Sea is not at all isolated from busy international commercial shipping lanes. Numerous other countries also surround the South China Sea, which means that the presence of foreign navies is inevitable. The relatively complex underwater sound environment in the South China Sea makes China’s submarines easier to hide but also makes it more difficult for China to find and dispatch foreign attack submarines. Unlike Russian submarine bastions, the South China Sea—located south of the Tropic of Cancer—is never covered by sea ice, which if present could have provided important protection for SSBNs. For these reasons, China faces greater challenges in creating a safe submarine haven in the South China Sea today than the Soviets did in their coastal waters during the Cold War.

Implications for China’s Nuclear Policy and Future Challenges

As mentioned above, China does not seek to use SSBN for any additional missions beyond minimum nuclear deterrence. Tactical strikes on military targets or escalation management through “flexible nuclear response” do not fall in line with current Chinese domestic discussions or official government policy and is not, in any case, the best use of an SSBN. The main strategic objective is to bolster China’s overall nuclear deterrent, to the extent that the country’s nuclear retaliation capability has unambiguous credibility. With this said, the introduction of the sea-based nuclear weapons will have important implications for China’s nuclear policy and may affect perceptions of China’s nuclear posture in other countries. Therefore, China needs to make careful choices to avoid changing its restrained nuclear posture and to adequately address the issue of conventional-nuclear entanglement.

First, SSBNs may quickly change people’s calculations of China’s strategic nuclear capabilities. A widely cited assessment puts China’s existing nuclear stockpile at about 180 warheads (excluding warheads on SLBMs).61 Of this stockpile, only about 45 ICBMs can potentially reach the continental United States.62 However, if China succeeds in fielding between five and eight 094-class SSBNs in the near future, as some top U.S. government officials predict,63 China will add between 60 and 96 strategic missiles that could potentially hit the continental United States.64 Admittedly, it is unlikely that all SSBNs could be in patrol areas and be ready to launch against the United States at the same time; this is just the total number of SLBMs that in theory could strike the continental United States. Moreover, if the JL-2 SLBMs can, as some claim, carry more than one warhead, the number of warheads that in theory could reach the continental United States would increase much more.65 No information is available about whether the SLBM warheads would come from new stock or be diverted from existing stock. But in either case, a new SLBM strike capability unquestionably would affect the threat perceptions of foreign countries, especially the United States. American officials and experts are already alarmed by the rapid increase of China’s nuclear capabilities, and they feel very uneasy about future development prospects.66 Even though China’s expressed nuclear intentions have remained completely defensive, changing the U.S. threat perception could very well exacerbate the existing security dilemma between the two major nuclear powers.

Second, the deployment of SSBNs poses a new challenge to China’s restrained nuclear posture. It is believed that China has maintained a very low alert level for its land-based nuclear missiles during peacetime. It is said that nuclear warheads are stored de-mated from missiles and are stored separately at different locations.67 This practice of separating warheads from missiles, however, would not be applied to China’s SSBN forces. It is common practice in the United States, Russia, Great Britain, and France to have the SSBNs carry SLBMs with warheads on them when conducting patrols. If China adopts the same strategy, it would be a major change to China’s long-term policy of separating warheads from missiles during peacetime. Furthermore, a greater concern expressed by foreign experts is that SSBN deployment may force China to pre-delegate missile launch authority to submarine commanders. This, they argue, may increase the chances of unauthorized or accidental launches.68

Still, China does have options for mitigating the problem, but these options are rarely discussed. From the perspective of maintaining deterrence, China does not have to always arm its SLBMs with nuclear warheads; nor do all SSBN patrols have to carry SLBMs in peacetime. As long as China does not reveal whether its SSBNs on patrols carry missiles, or whether the missiles carry warheads, potential enemies will have to assume that they do. Additionally, China can choose to arm its patrolling SSBNs with missiles and warheads in some instances but not in others. Again, without revealing which SSBN on which patrol mission carries missiles and warheads, potential enemies will have to assume the worst case scenario and treat each Chinese SSBN on patrol as fully armed. Such strategies will not undermine the credibility of China’s sea-based nuclear deterrence during peacetime, but either can reduce the dangers associated with carrying real warheads and minimize the consequences of SSBN incidents at sea. When a crisis emerges, China can then start arming all its SSBNs on patrols. In actuality, military tensions take time to build up, and a security crisis that is serious enough for China to contemplate nuclear retaliation also takes time to develop and escalate. Therefore, there is always time for China to be warned of such a crisis and have sufficient time to arm its SSBNs.

Admittedly, there are also other issues for Chinese decisionmakers to consider when it comes to the question of whether China should deploy missiles and warheads during their SSBN patrols. Conducting patrols without missiles or warheads may have a negative impact on force morale. More important, if SSBN crews are not trained frequently to operate with missiles and warheads during peacetime, they might be prone to making mistakes with maneuvers like loading warheads onto missiles under high-pressure environment during crisis. Of course, China will need to take careful measures to keep the information of which patrols are deployed with or without missiles and warheads from dedicated foreign intelligence activity. In addition, if China chooses not to always deploy missiles and warheads on submarines, the act of loading missiles and warheads during crisis could be read by potential adversaries as an act of serious escalation. This problem might be mitigated if China—as reported—possesses large underground and underwater facilities where the loading of missiles/warheads can take place without being spotted from the air.69 Ultimately, the Chinese policymakers will need to make a decision, but it does not have to be a fixed and final decision. China certainly can and should adjust its policy as circumstances change, and as it gains experience and takes lessons from its own and others’ practices.

With regard to whether China should pre-delegate nuclear missile launch authority to submarine commanders, the answer does not have to be “yes” either. China’s SSBN is controlled by the People’s Liberation Army (PLA) Navy, rather than the Second Artillery Force.70 Some military commentators suggest that, with the recent establishment of the new service branch—the PLA Rocket Force—which has replaced the Second Artillery Force as a result of the Chinese military reform, all Chinese nuclear capabilities, including land-, sea-, and air-based nuclear weapons, will be incorporated into and managed by the Rocket Force.71 Nonetheless, there has been no official confirmation regarding SSBNs becoming part of the Rocket Force. Regardless of which service branch will control the SSBNs, it is abundantly clear that all Chinese nuclear forces, including strategic nuclear submarines, are under direct command and control from the Central Military Commission. The respective military service branches have no authority to issue launch order to nuclear forces.72

In some countries, including the United Kingdom, SSBN commanders can resort to a letter locked in a safe on the submarine to follow the prewritten order and carry out necessary operations in the case that command and control ashore is destroyed or unreachable. In the case of the U.S. SSBN, only higher authorities ashore have the code to unlock a submarine’s launch key safes, which they transmit to submarine officers when a launch is ordered. Without the code from a higher authority, the submarine crew cannot independently launch any missiles.73 To adopt such a policy requires reliable communication between the national authority and the SSBN. In the Chinese case, although foreign government reports and some experts doubt the capability of the Chinese leadership to communicate with its nuclear submarines at sea, there has been impressive progress in recent years.74 China is now capable of communicating with its submarines at super low frequency (SLF). Its airborne, long-wave submarine communication technology is also reportedly under development.75 As early as 2013, Chinese nuclear attack submarines completed a patrol through the Indian Ocean and sailed all the way to the Gulf of Aden.76 This demonstrated China’s growing capability to communicate with nuclear submarines from a very long distance.

Another issue is whether China needs to maintain a so-called continuous-at-sea deterrence. This deterrence posture requires a country to maintain at least one SSBN in patrol areas at any given time. This posture has been adopted by most other nuclear weapons states, but whether it is a favorable option for China requires systematic examination. Some Chinese military commentators presume that constant SSBN patrol is the ultimate goal for China to pursue, and the fact that China has built at least four 094 SSBNs seems to confirm such speculation. However, there has been no open discussion about why China needs to maintain a continuous-at-sea deterrence. Instead, China has long held the view that a nuclear war between nuclear weapons states is very unlikely to break out, let alone a completely “out of the blue” surprise nuclear first strike that the continuous-at-sea policy seeks to deter.77 Looking toward the future, China can safely maintain the credibility of its nuclear deterrence by continuing its relatively restrained nuclear posture without embracing a continuous-at-sea posture during peacetime. With the underwater entry and exit at the Sanya submarine base, Chinese SSBNs may be able to leave port undetected.78 If this is the case, flushing Chinese SSBNs out during crises will not cause the problem of misinterpretation and inadvertent escalation. The downside of intermittent patrols is that submarines will be subject to preemptive strikes (even conventional preemptive strikes) in port. To address this problem, China will need to quickly deploy its SSBNs to sea as soon as the first sign of a serious military crisis emerges. Also, China will need to come up with effective crew training and equipment maintenance mechanisms to compensate for the lack of continuous-at-sea training opportunity.

Finally, China’s deployment of SSBNs needs to address the increasing interaction between conventional and nuclear assets. Currently, all Chinese nuclear weapons are deployed within Chinese territory. With SSBNs operating at sea, there is always a chance of foreign conventional military assets directly confronting Chinese nuclear weapon delivery systems. The United States, together with its regional allies, has already made great efforts to revitalize their ASW capability in the Asia-Pacific region. With the number of U.S. maritime surveillance aircrafts and attack submarines deployed in the region having increased, the U.S. Navy has explicitly expressed interest in trailing and tracking Chinese SSBNs.79 As early as the mid-2000s, there were reports of joint naval exercises between the United States and its regional allies to hunt down strategic nuclear submarines from “Country C.”80 Given that current Chinese SSBNs are not sufficiently quiet, they are more likely to open themselves to threats than are their counterparts in other advanced nuclear weapons states. Before China’s SSBNs can rely on their own stealth to achieve credible survivability, Beijing will need to depend somewhat on friendly forces to protect them. This increases the chances of conventional military confrontation between China and its potential adversaries.

Despite the United States’ commitment in declaratory policy to “maintaining strategic stability” with China—which implies the United States would not intentionally undermine China’s strategic nuclear deterrent—the U.S. Navy has a number of tactical incentives to hunt down Chinese SSBNs.81 Strategic ASW against Chinese SSBNs can force China to withdraw nuclear attack submarines (SSN) into protecting its SSBNs, thereby leaving Chinese SSNs unavailable to threaten U.S. aircraft carriers and other surface ships.82 The United States adopted such a strategy against the Soviet Union during part of the Cold War. Also, aware of the difficulty of intercepting SLBMs, the U.S. Navy is incentivized to counter Chinese SSBNs before any missile can be launched.83 Furthermore, the United States has shown considerable interest in using new technologies like unmanned underwater drones to track and trail Chinese SSBNs. There have been specific government-sponsored studies about how to deploy underwater drones close to Chinese submarine bases to detect Chinese SSBNs as they leave and return to port.84 Chinese SSBNs at sea are likely to face challenges from the most advanced ASW platforms in the world.

This may impose new pressure on China’s unconditional no-first-use (NFU) policy. If Chinese SSBNs are confronted by rigorous ASW operations, the Chinese leadership may feel that their strategic nuclear deterrent is under direct threat from an enemy’s conventional weapons. This would put China in a real dilemma: Should China continue to uphold an unconditional NFU policy? China knows full well that maintaining a policy of unconditional NFU will restrain Chinese response options if an SSBN is sunk by a conventional attack and will very likely encourage the enemy to vigorously track and trail Chinese SSBNs absent the risk of a forceful response. So far, China has not indicated that it is reconsidering NFU policy after the introduction of SSBNs. Whether it may do so in the future depends on how much of an ASW threat China perceives from potential adversaries. It would therefore be very helpful for China, the United States, and other regional countries to discuss these issues and avoid unnecessary misunderstandings and overreactions.

Intensified cat-and-mouse games between Chinese SSBNs and enemy ASW platforms in China’s coastal waters have greatly increased the risks of conventional military conflicts. Potentially dangerous encounters between the Chinese and U.S. militaries are increasing in number; recently, the United States has ramped up its aerial maritime surveillance over the South China Sea to hunt down Chinese nuclear submarines, and China has many times scrambled fighter jets to intercept American P-8A ASW aircraft.85 Similar incidents have also occurred between U.S. surveillance vessels, which were mapping the sea floor close to China’s nuclear submarine base, and Chinese naval ships and maritime militia.86 Such dangerous encounters might grow in number as the United States, and others appear to be taking more counteractions to undermine Chinese efforts to establish an SSBN bastion in part of the South China Sea as a near-term alternative to open-ocean patrols. At this moment, the main players are close to embarking on a collision path with each other, with no easy solution in sight. Because conventional conflicts that involve SSBNs have the potential to escalate to the nuclear level, it is very important for all parties to clearly understand the risks and stakes in this dangerous interaction. The close surveillance activities by the U.S. military in the Chinese coastal area, for instance, should be reduced. The shared common interests of all countries to avoid conflict scenarios should motivate relevant parties to take the escalation issue seriously and have candid discussions on how to avoid misunderstanding and mitigate potential security risks.

Conclusion

In conclusion, China’s investment in a sea-based nuclear deterrent capability is driven by the perceived vulnerability of China’s existing nuclear forces in light of the challenges posed by new strategic military technologies. However, it takes time for China to build a genuinely quiet SSBN fleet and to obtain adequate operational experience. Before this can be done, China’s SSBN deployment will be constrained and its deterrence value undercut. The maritime environment in Chinese coastal waters also creates problems for China about building submarine bastions in South China Sea or Yellow Sea. As a result, China may need to rely on friendly forces to ensure the survivability of its current SSBN fleet.

Looking toward the future, China can embrace an operational strategy that maintains a meaningful but moderate patrol frequency and that refrains from keeping very high alert status during peacetime. This will maximize the deterrence value of its sea-based nuclear capability, without inadvertently undermining regional security. Better communication and coordination among all regional players are also important to avoid negative interactions and maintain regional stability.

Tong Zhao is an associate in Carnegie’s Nuclear Policy Program based at the Carnegie–Tsinghua Center for Global Policy.

Notes

1 Andrew S. Erickson and Lyle J. Goldstein, “China’s Future Nuclear Submarine Force: Insights from Chinese Writings,” Naval War College Review 60, no. 1 (Winter 2007): 55–79; Hans M. Kristensen, Robert S. Norris, and Matthew G. McKinzie, Chinese Nuclear Forces and U.S. Nuclear War Planning (Washington, DC: Federation of American Scientists and Natural Resources Defense Council, 2006); Ronald O’Rourke, China Naval Modernization: Implications for U.S. Navy Capabilities—Background and Issues for Congress (Washington, DC: Congressional Research Service, 2008).

<2 Office of the Secretary of Defense, Annual Report to Congress: Military and Security Developments Involving the People’s Republic of China 2015 (Washington, DC: U.S. Department of Defense, 2015).

3 Hearings on U.S. Pacific Command Posture, Before the Senate Armed Services Committee,114th Cong., statement of Admiral Samuel J. Locklear, U.S. Navy, commander, U.S. Pacific Command, April 16, 2005.

4 Office of the Secretary of Defense, Annual Report to Congress: Military and Security Developments Involving the People’s Republic of China 2016 (Washington, DC: U.S. Department of Defense, 2016).

5 Xiang Ling, “Birth of the Chinese Nuclear Submarine,” Modern Weapons, no. 11 (2001): 35–37.

6 Ningjun Fu, “Peng Shilu and China’s Nuclear Submarine,” Yanhuang Chunqiu, no. 1 (1998): 23–26.

7 Ibid.

8 Zhu Yu, “China Had No Choice: History of the Development of the Missile Nuclear Submarine,” Science Times, no. 2 (1998): 17–21.

9 Xiping Ding, “‘Nuclear Submarines Will Be Built, Even If It Takes Ten Thousand Years’”: Interview with the Chief Designer Peng Shilu and Deputy Chief Designer Zhao Renkai of Our Country’s First Nuclear Submarine,” China’s Nuclear Industry 5 (1999): 21–23.

10 Feng Ding and Lan Wei, The Path of China’s Nuclear Submarines: Commemorating the Fortieth Anniversary of the Deployment of the First Nuclear Submarine (Beijing: High-Level Forum on the Two “Dans” and One “Xing,” 2014).

11 Changxue Shi, Naval Commander Liu Huaqing (Beijing: Long March Press, 2013).

12 Lyle J. Goldstein and Andrew S Erickson, China’s Nuclear Force Modernization (Newport, RI: Naval War College Center for Naval Warfare Studies, 2005).

13 Bin Li, “China’s Nuclear Strategy,” World Economics and Politics,no. 9 (2006): 16–22; Yu Rong and Yuan Hong, “The Evolution of China’s Nuclear Strategy: From Antinuclear Deterrence to Limited Deterrence,” Journal of Contemporary Asia-Pacific Studies, no. 3 (2009): 120–32.

14 The stealthiness, of course, depends on how quiet the submarine can be. This is a discussion about ideal conditions.

15 Fei Li, “Limitations of Antisubmarine Operations,” Foreign Naval Development Collection, no. 2 (2002): 35–38.

16 Chunbo Tao, “Analysis of Numerical Demands for Strategic Nuclear Submarines in Nuclear Powers,” Ship Engineering, no. 5 (1998): 56–58.

17 Lianxin Yang, “Ballistic Missile Nuclear Submarine and National Security,” Modern Ships, no. 9 (1995): 4–5.

18 Bin Li and Hongyi Nie, “A Study of Sino-U.S. Strategic Stability,” World Economics and Politics, no 2 (2008).

19 Riqiang Wu, “The Survivability of China’s Sea-Based Nuclear Forces,” Science & Global Security 19, no. 2 (2011): 93, 96, 104.

20 Xiaosong Shou, The Science of Military Strategy (Beijing: Military Science Press, 2013).

21 Wei Guo, Qingxuan Yang, and Qiang Su, “Research on the Trend of Development of Foreign Ballistic Missile Nuclear Submarines,” Ship Science and Technology 37, no. 7 (2015): 233–37.

22 Ibid.

23 Yang, “Ballistic Missile Nuclear Submarine and National Security.”

24 Office of Naval Intelligence, The People’s Liberation Army Navy: A Modern Navy with Chinese Characteristics (Washington, DC: Office of Naval Intelligence, 2009).

25 Wu, “Survivability.”

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

27 Lianxin Yang, “Four Stages of China’s Nuclear Submarine Development,” China Nuclear Industry,no. 11 (2013): 57–60.

28 Wu, “Survivability”; Jianwei Tian, “094 Nuclear Submarine: China’s ‘King of South China Sea,’” Communists, no. 8 (2014): 60–61.

29 Yang Shi and Yazhou Xi, “Farewell, the ‘Youth Era’ of Chinese Nuclear Submarine,” Military Culture, no. 11 (2013): 64–67.

30 Riqiang Wu, “Has China’s Strategic Nuclear Submarine Started Operational Patrols?,” Modern Ships, no. 2 (2016): 32–36.

31 Sina Military, Preliminary Analysis on Why China Has Not Established a Missile Nuclear Submarine Operational Patrol Mechanism (Beijing: Sina Military, 2016). It is necessary to note that there are some exceptions. For example, American SSBNs do sometimes make publicly announced port calls to foreign countries.

32 Wu, “Has China’s Strategic Nuclear Submarine Started Operational Patrols?”

33 Wenhan Hu, Chuanchao Liu, and Dachao Zhou, “China’s Emerging Ballistic Missile Nuclear Submarine,” Global Military, no. 23 (2013): 66; Tao Wen, “How Can China’s Nuclear Submarine Effectively Deter the United States?,” Modern Ships, no. 19 (2015): 30–42.

34 Toshi Yoshihara and James R. Holmes. “China’s New Undersea Nuclear Deterrent: Strategy, Doctrine, and Capabilities,” Joint Forces Quarterly, no. 50 (2008).

35 Iskander Rehman, “Murky Waters: Naval Nuclear Dynamics in the Indian Ocean,”Carnegie Endowment for International Peace, March 9, 2015, http://carnegieendowment.org/2015/03/09/murky-waters-naval-nuclear-dynamics-in-indian-ocean; Brendan Thomas-Noone and Rory Medcalf, Nuclear-Armed Submarines in Indo-Pacific Asia: Stabiliser or Menace? (Sydney: Lowy Institute for International Policy, 2015); Yoshihara and Holmes, “China’s New Undersea Nuclear Deterrent.”

36 Chaoping Du, “Indian ‘Nuclear Train’ Speeding Up in April,” China National Defense News; Jiegen Zhang, “Implications of Indian Nuclear Strategy for China’s Security Environment and South Asia Policy,” Tongji University Journal, Social Science Section 22, no. 2 (2011): 65–71.

37 Alastair Iain Johnston, “China’s New Old Thinking: The Concept of Limited Deterrence,” International Security 20, no. 3 (1995): 5–42.

38 Alastair Iain Johnston, “Prospects for Chinese Nuclear Force Modernization: Limited Deterrence versus Multilateral Arms Control,” China Quarterly,no. 146 (1996): 548–76.

39 Tianfu Wu, International Nuclear Strategy Thinking (Beijing: Yi Wen Publishing Military, 1999); Guangyu Xu, Aspects of Nuclear Strategy (Beijing: National Defense University Press, 1987).

40 Johnston, “China’s New Old Thinking.”

41 Samuel Bell, The Impact of the Type 094 Ballistic Missile Submarine on China’s Nuclear Policy (Monterey, CA: Naval Postgraduate School, 2009).

42 Xiangli Sun, Strategic Choice in the Nuclear Age: On China’s Nuclear Strategy (Beijing: Center for Strategic Studies of the Chinese Academy of Engineering Physics, 2013).

43 Ibid.

44 Kier A. Lieber and Daryl G. Press, “The End of MAD? The Nuclear Dimension of U.S. Primacy,” International Security 30, no. 4 (2006): 7–44; “U.S. Nuclear Primacy and the Future of the Chinese Deterrent,” China Security, Winter 2007, 66–89.

45 Fan Chen, “The Second Nuclear Force: History of China’s Nuclear Submarine Development,” Shipboard Weapon, no. 4 (2007): 38–43.

46 Lu Hong, “Sea-Based Nuclear Deterrent of the People’s Navy,” Shipboard Weapon, no. 1 (2004): 28–34; Yang, “Ballistic Missile Nuclear Submarine and National Security.”

47 Linton Brooks, “Strategic Stability and Submarine Operations: Lessons from the Cold War,” in Confidence-Building and Maritime Strategic Stability in the Asia-Pacific (Beijing: Carnegie-Tsinghua Center for Global Policy, 2015).

48 Bryan Clark, The Emerging Era in Undersea Warfare (Washington, DC: Center for Strategic and Budgetary Assessments, 2014); Walter M. Kreitler, The Close Aboard Bastion: A Soviet Ballistic Missile Submarine Deployment Strategy (Monterey, CA: Naval Postgraduate School, 1988).

49 Debin Du, Yahua Ma, Fei Fan, and Caixing Yun, “China’s Maritime Transportation Security and Its Measures of Safeguard,” World Regional Studies 24, no. 2 (2105): 1–10; Jinyang Hu, “The Julang Sweeping through the West Pacific Ocean,” Aeronautical Knowledge, no. 1 (2014): 49–51; Qin Shi, “History of Ballistic Missile Nuclear Submarine Operational Patrols,” Modern Ships, no. 2 (2016): 37–42; Wen, “How Can China’s Nuclear Submarine Effectively Deter the United States?”

50 The U.S. missile defense system is primarily aimed at intercepting missiles flying over the North Pole and is less capable of intercepting missiles launched from the Southern Pacific. See, for example, Wu, “Has China’s Strategic Nuclear Submarine Started Operational Patrols?”

51 Office of the Secretary of Defense, Annual Report to Congress; Hans M. Kristensen and Robert S. Norris, “Chinese Nuclear Forces, 2015,” Bulletin of the Atomic Scientists 71, no. 4 (2015): 77–84.

52 The First Island Chain refers to the first major archipelagos off the East Asian continental mainland, including the Japanese archipelago, the Ryukyu Islands, China’s Taiwan, and the northern Philippines. See, for example, Li Xiaokun, “China Sails Through ‘First Island Chain,’” China Daily,2013.

53 Desmond Ball and Richard Tanter, The Tools of Owatatsumi: Japan’s Ocean Surveillance and Coastal Defence Capabilities (Canberra: Australian National University Press, 2015); Lyle J. Goldstein and Shannon Knight, “Wired for Sound in the ‘Near Seas,’” Proceedings of the U.S. Naval Institute 140, no. 4 (2014): 56–61; Owen R. Cote, Assessing the Undersea Balance Between the U.S. and China,Security Studies Program Working Paper (Cambridge, MA: Massachusetts Institute of Technology, 2011).

54 Yifeng Wang and Jing Ye,“Lessons for China’s Nuclear Submarine Penetration from the Sino-Japanese Nuclear Submarine Incident,” Shipboard Weapon, no. 1 (2005): 27–31.

55 Wen, “How Can China’s Nuclear Submarine Effectively Deter the United States?”

56 “Domestically Made Aircraft Carrier Will Still Use Ski-Jump Take Off: Main Mission Is to Cover Nuclear Submarine at Sea,” Sohu Military,January 18, 2014.

57 O’Rourke, China Naval Modernization; Christopher H. Sharman, China Moves Out: Stepping Stones toward a New Maritime Strategy (Washington, DC: Center for the Study of Chinese Military Affairs, Institute for National Strategic Studies, National Defense University, 2015).

58 Hans M. Kristensen, “China SSBN Fleet Getting Ready—But for What?” Federation of American Scientists, April 25, 2014.

59 Wu, “Survivability of China’s Sea-Based Nuclear Forces.”

60 Office of the Secretary of Defense, Annual Report to Congress.

61 Kristensen and Norris, “Chinese Nuclear Forces, 2015.”

62 According to Hans M. Kristensen and Robert S. Norris’s assessment, the total number of DF-5A, DF-5B, and DF-31A missiles is about 45.

63 Hearings on U.S. Pacific Command Posture, Before the Senate Armed Services Committee.

64 Admittedly, it is unlikely that all SSBNs can be in patrol areas and ready to launch against the United States at the same time. This is just the total number of SLBMs that in theory can strike the continental United States.

65 “JL-2 (CSS-NX-14),” GlobalSecurity.org.

66 Richard Weitz, “U.S.-China Commission Underscores Growth in Chinese Nuclear Strike Potential,” Second Line of Defense, 2012.

67 Paul H. B. Godwin, Potential Chinese Responses to U.S. Ballistic Missile Defense (Washington, DC: Stimson Center and Center for Naval Analyses, January 17, 2002); Kristensen, Norris, and McKinzie, Chinese Nuclear Forces.

68 Bell, The Impact of the Type 094 Ballistic Missile Submarine; David J. Elkind, American Nuclear Primacy: The End of MAD or a New START? (Washington, DC: Center for Strategic and International Studies, 2012).

69 David S. McDonough, “Unveiled: China’s New Naval Base in the South China Sea,” National Interest, March 20, 2015.

70 The China defense white paper that was published in 2013 mentions that the Second Artillery Force “has a series of ‘Dong Feng’ ballistic missiles and ‘Chang Jian’ cruise missiles.” Therefore, the “Ju Lang” submarine-launched ballistic missiles are not managed by the Second Artillery.

71 “Expert: PLA Rocket Force Might Have Strategic Nuclear Submarine and Strategic Bomber,” China News Network, January 7, 2016.

72 State Council Information Office of the People’s Republic of China, The Diversified Employment of China’s Armed Forces (Beijing: State Council Information Office of the People’s Republic of China, May 2013.

73 Douglas C. Waller, “Practicing for Doomsday,” Time,March 4, 2001.

74 Office of the Secretary of Defense, Annual Report to Congress.

75 Wu,“Has China’s Strategic Nuclear Submarine Started Operational Patrols?”

76 Vijay Sakhuja, “Chinese Submarines in Sri Lanka Unnerve India: Next Stop Pakistan?” China Brief 15, no. 11 (2015): 15–18.

77 Fiona S. Cunningham and Taylor M. Fravel, “Assuring Assured Retaliation: China’s Nuclear Posture and U.S.-China Strategic Stability,” International Security 40, no. 2 (2015): 7–50.

78 Bell, Impact of the Type 094 Ballistic Missile Submarine.

79 David S. Cloud, “Aboard a U.S. Nuclear Sub, a Cat-And-Mouse Game with Phantom Foes,” Los Angeles Times,September 25, 2015.

80 Wang and Ye, “Lessons for China’s Nuclear Submarine Penetration from the Sino-Japanese Nuclear Submarine Incident: Anti-Submarine Capability of China, the U.S., Japan, and Taiwan.”

81 U.S. Department of Defense, United States Nuclear Posture Review Report (Washington, DC: U.S. Department of Defense, 2010).

82 Goldstein and Erickson, China’s Nuclear Force Modernization.

83 Ibid.

84 Robert W. Button, John Kamp, Thomas B. Curtin, and James Dryden, A Survey of Missions for Unmanned Undersea Vehicles (Santa Monica, CA: National Defense Research Institute of the RAND Corporation, 2009).

85 Zachary Keck, “China’s ‘Dangerous Intercept’ of U.S. Spy Plane,” Diplomat, August 23, 2014.

86 Thom Shanker, “China Harassed U.S. Ship, Pentagon Says,” New York Times, March 10, 2009.