Table of Contents

Of all the aspects of China’s SSBNs, their overall survivability is the most important factor in determining their impact on strategic stability. Survivability refers to an SSBN’s capability—through stealth, supporting forces, and other means—to remain safe from an enemy’s ASW efforts and, if needed, deliver SLBMs through an enemy’s missile defenses to strike their targets.

SSBN survivability has a significant impact on crisis stability. If China were concerned that its SSBNs could be destroyed, it would have a greater incentive to use the nuclear weapons onboard early in a conflict—even at the first sign of a preemptive strike by an adversary—before the weapons were lost. Moreover, concern about SSBN survivability could lead China to employ pro-SSBN forces (friendly general-purpose forces used to protect SSBNs) in aggressive ways to counter an enemy’s ASW capabilities, raising the risk of a conventional military conflict. Because such a conflict would be fought in the presence of SSBNs, it would unfold under the nuclear shadow and carry a greater risk of escalation.

Of all the aspects of China’s SSBNs, their overall survivability is the most important factor in determining their impact on strategic stability.

SSBN survivability also seriously affects arms race stability. China’s accelerated investment into its SSBN program in recent years has been partially driven by concerns about the overall credibility of its nuclear deterrent. If Beijing feels its existing SSBN fleet falls short of what is required for a credible deterrent, it will likely increase its investment and build more and better SSBNs. These actions could, in turn, increase threat perceptions in other countries and intensify the existing competition. The arms competition resulting from Chinese efforts to protect its SSBNs and from other countries’ countermeasures could extend into the domain of conventional forces, including even unmanned vessels.

The Inherent Survivability of Chinese SSBNs

China’s expectation that its SSBNs can help enhance the credibility of its second-strike capability is based on the assumption that the SSBNs are—or at least can become—highly survivable. China has undertaken great efforts in recent years to augment the survivability of its nuclear-armed submarines, although there are still real challenges to ensure that the submarines remain undetected while they are operating.

There is very limited information available today about how quietly Chinese SSBNs can operate, but international and Chinese experts generally agree that China’s 094-class SSBN is relatively noisy. According to a 2009 assessment by the U.S. Office of Naval Intelligence, this SSBN is noisier than the Russian Delta III SSBN, which was developed in the 1970s.1 Wu Riqiang, a Chinese scholar at Renmin University, has used open sources to estimate an answer. He found that the low frequency noise level (100 hertz)—a widely used indicator of submarine quietness—attributed to China’s 094-class SSBN is significantly higher than that of the Russian Delta IV SSBN. For the time being, at least, the Delta IV forms the backbone of Russia’s SSBN fleet and is noisier than the United States’ current generation of Ohio-class SSBNs.2

In some respects, the design of China’s submarines may be refined over time. Notably, when China was developing its first-generation nuclear submarines, it built a prototype vessel first, as quickly as possible, and then improved the design for subsequent vessels.3 China’s leadership may be adopting the same strategy for its second-generation submarines.4 While the first vessel of the 094 class may be relatively noisy, it is possible, therefore, that subsequent vessels of the same class may perform better. In fact, recent photos of a new 094-class SSBN revealed some new design and manufacturing features; these changes seem so significant that some Chinese analysts have described the boat as belonging to a new class: the 094A.5 These submarines may become more survivable than the original 094 class, particularly in China’s shallow coastal waters (where detecting quiet submarines is particularly challenging).

Some of the basic design features of the 094 class seriously limit its potential to become a genuinely quiet submarine.

That said, some of the basic design features of the 094 class seriously limit its potential to become a genuinely quiet submarine. The submarine’s large missile compartment, the numerous flood openings in the casing, and the skewed propeller (among other basic design features) make it very difficult to significantly reduce the submarine’s noise level.6 Indeed, Russia and Western states succeeded in developing quiet SSBNs by making noise reduction a fundamental driving parameter of their design and construction. By contrast, China still has some way to go in terms of improving its submarine technology and obtaining operating experience.

To make matters worse, China’s SSBNs may be even noisier than Wu concluded, given certain operating parameters. His assessment that the 094-class SSBN is too noisy to be survivable was based on the average ambient low-frequency noise level in the shelf region of the northern South China Sea. However, ambient noise in that region is usually much higher than in deep ocean water. Consequently, the detection range of the same SSBN in deep ocean water would be much longer. In other words, China’s SSBNs would be less survivable in deep ocean water than in shallow coastal waters.

And there is another reason that Chinese SSBNs may be even noisier during patrols than Wu’s assessment indicates. Wu focused on noise at very low speeds of around 4–8 knots (approximately 4–9 miles per hour). Most Chinese experts claim that SSBNs usually operate at such low speeds in their patrol areas to avoid cavitation—a form of noise generation involving the collapse of air bubbles created by a propeller. However, other Chinese experts assert that, even in patrol areas, SSBNs usually operate at speeds of around 15–16 knots (or about 17–18 miles per hour), much higher than the cavitation threshold speed of about 8 to 10 knots (or roughly 9–11.5 miles per hour).7

Another factor affecting the survivability of Chinese SSBNs is their maximum operating depth. Generally, the deeper underwater a submarine is located, the weaker its acoustic signature is, making it more difficult to detect. Moreover, deep water offers a better operating environment for the submarine’s own sonar, enhancing its ability to detect threats.8 The survivability of China’s SSBNs may, therefore, be further reduced by reported limitations on their capability to dive deeply.9

Despite such limitations, there are ways for China to maximize the deterrent value of its existing SSBNs.

Despite such limitations, there are ways for China to maximize the deterrent value of its existing SSBNs. Although the 094 class may be too noisy to be truly survivable in open-ocean patrols, there is a good chance that it can operate relatively safely in coastal waters. If China uses general-purpose military forces to protect its SSBNs in these regions, their survivability would be further enhanced. Under this approach, the SSBNs would remain safe in China’s coastal waters and only seek to break out into the Pacific Ocean if a crisis occurred, so that their JL-2 SLBMs could reach the U.S. homeland.

In any case, the value of 094-class SSBNs to China may not be exclusively a matter of extant military capabilities. When discussing the role of China’s first-generation nuclear submarines, Chinese strategists have emphasized that the main objective was to acquire a baseline nuclear submarine capability even if it was somewhat barebones before later focusing on improving technological sophistication. Moreover, nuclear submarines serve as “schools and labs” of sorts for the Chinese navy in the sense that they help China “gain experience operating large and complex equipment” and “train next-generation sailors and technicians.”10 In a similar vein, even though China’s second-generation SSBNs are beginning to embark on deterrence patrols, a major part of their purpose may still be to provide their crews with operational experience.11

In the long run, Chinese analysts are optimistic that the country’s future SSBNs will be sufficiently quiet to be militarily effective. They point to evidence that China has been conducting research on a range of new technologies such as pump-jet propulsion and high-temperature, gas-cooled nuclear reactors, and they predict that these new technologies will soon be incorporated into new submarines.12

In May 2017, a CCTV broadcast highlighted the achievements of Rear Admiral Ma Weiming, an academic at the Chinese Academy of Engineering and the director of the Power Electronics Research Institute at the PLA Naval Engineering University. On the CCTV program, Admiral Ma claimed that China’s shaftless, rim-driven, pump-jet technology is more than ten years ahead of that of the United States; moreover, he claimed that the technology is designed for China’s “next-generation nuclear submarine” but is already being used in some areas now.13 Given that China’s nuclear submarine propulsion technology has lagged considerably behind that of other major powers for the past several decades, questions were raised about the credibility of this bold claim. That said, if China has made a technological breakthrough, it may now be able to quickly and significantly increase the quietness and thus the survivability of its SSBNs.

The Survivability Implications of Open-Ocean Deployment

In addition to the structural design of SSBNs, the manner in which these vessels are deployed is another important factor for determining their survivability. Internal Chinese discussions focus on two main potential deployment strategies. One approach, similar to the one the United States employs, is to have submarines conduct patrols in the open ocean. When used in this way, SSBNs must remain quiet enough to rely primarily on their own stealth capabilities to transit to the patrol area and stay undetected during the patrol period.14 The second strategy, reminiscent of Soviet policy in the later years of its SSBN operations, is to deploy SSBNs to designated areas (termed bastions) in coastal waters. Within these bastions, SSBNs can be protected from advanced enemy ASW capabilities by general-purpose forces.15

The available evidence suggests that Chinese SSBNs are not yet conducting regular open-ocean patrols but that Beijing may already be preparing for a future in which they do. Indeed, going forward, China has strong incentives to have its SSBNs patrol in the open ocean—in the Pacific, in particular; many Chinese strategists believe this is China’s long-term goal.16 Some senior PLA scholars have argued that open-ocean SSBN patrols are a “necessary capability” in the long-term future.17

One major reason Chinese analysts assume that Beijing hopes to eventually conduct regular open-ocean patrols is because of the limited range of the JL-2 ballistic missiles that its SSBNs carry (7,200 kilometers).18 Given that, JL-2 missiles cannot reach the continental United States if launched from Chinese coastal waters. At a minimum, Chinese SSBNs would have to sail into the Western Pacific to target the U.S. mainland with this missile. If putting the continental United States in missile range is a primary goal of the Chinese military, the country’s leadership, therefore, has a strong incentive to send its 094-class SSBNs into the open ocean as soon as possible.

In addition to the structural design of SSBNs, the manner in which these vessels are deployed is another important factor for determining their survivability.

As mentioned previously, the operational future and potential range of China’s next-generation JL-3 SLBM remain uncertain. The most recent U.S. Worldwide Threat Assessment report, released by the director of national intelligence on February 13, 2018, states that “the PLA Navy continues to develop the JL-2 submarine-launched ballistic missile.”19 This may imply that the next-generation JL-3 will not become operational in the immediate near-term future.

In addition, conducting patrols in the open ocean would give China’s SSBNs much greater flexibility in terms of patrol areas and launch positions. Chinese experts emphasize the importance of large patrol areas and the ability to surprise an enemy by operating from unpredictable launch locations as ways to greatly enhance deterrence.20 Furthermore, Chinese SLBMs launched from the Pacific would have shorter flight times and more unpredictable attack trajectories, compared to ICBMs launched from mainland China or SLBMs launched from Chinese coastal waters, so Pacific-launched SLBMs would enjoy an enhanced ability to penetrate U.S. missile defense systems.

Open-ocean patrols have other strengths as well. From a cost-saving perspective, China should have strong incentives to conduct open-ocean patrols. Submarines that are sufficiently quiet to survive and operate in open oceans on their own reduce operating costs significantly, compared to those that require protection by friendly forces. U.S. Ohio-class SSBNs, for example, are capable of safely transiting from their home ports to patrol areas in the open ocean and then conducting patrols with a minimum level of friendly force protection. By comparison, for part of the Cold War, the Soviet Union assigned a large portion of its navy’s general-purpose forces to protect SSBNs within bastions near its own coast, leaving the navy with insufficient resources for other operations.21 One final advantage of open-ocean patrols—as Chinese experts, including retired Rear Admiral Yin Zhuo, have pointed out—is that China’s coastal waters, especially the East China Sea, are not deep enough (about 100 meters deep on average) for China’s nuclear and conventional submarines to conduct proper training; he posits that the country’s submarines therefore naturally need to go to the Pacific.22

For its part, China’s anti-access area denial (A2/AD) capabilities also face challenges in creating a highly reliable SSBN safe zone in its coastal waters. China has reportedly developed and deployed various A2/AD capabilities, designed (in part) to keep large enemy surface ships away from its coast. However, Chinese capabilities to hinder the operations of enemy submarines and aircraft, which could pose a serious threat to China’s SSBNs, are less sophisticated.

The downside of open-ocean patrols is that very quiet submarines are required. After a submarine arrives in its patrol area, it can travel very slowly to minimize noise and hence the risk of detection. It must, however, first transit from its port to the patrol area, and, if it is to do so in a reasonable amount of time, it needs to travel at somewhat high speeds. During this period, the submarine tends to be noisier and so more vulnerable to detection.

China’s relatively noisy SSBNs would face significant challenges transiting undetected to the Western Pacific. In transiting from the South China Sea or the Yellow Sea to the Pacific Ocean, Chinese submarines have to sail through channels adjacent to enemy-controlled territories in the so-called First Island Chain—a series of archipelagos off the East Asian continental mainland, including Japan, the Ryukyu Islands, China’s Taiwan, and the northern Philippines.23 Such channels are closely monitored by the United States, Japan, Taiwan, and often the Philippines. Due to the difficulty of making undetected SSBN transits, Chinese strategists have been particularly emphatic about the importance of noise control.24

Apart from seeking to develop quieter submarines, there are alternative approaches China might employ to enable its SSBNs to reach the Western Pacific safely. For instance, according to some independent Chinese analysts, Beijing could use surface vessels to escort an SSBN to the Western Pacific, and then the SSBN could break loose from the fleet and start to patrol independently.25 While it is impossible to verify whether the Chinese navy has actually adopted this tactic, it is worth noting that the frequency with which Chinese surface fleets have been sent into the Western Pacific to conduct training missions has increased considerably in recent years.26 Such flotillas have included submarine rescue ships on a more frequent basis. It is probable that one or more SSNs were included in these training missions. In the future, after these SSNs have mastered this operation, China may become confident that its SSBNs can try to do the same.

The Survivability Implications of Bastion Deployment

In the long run, if China’s future SSBNs become sufficiently survivable in the open ocean, they may be deployed periodically on the open seas. That said, depending on how successful such open-ocean deployment turns out to be, China may still choose to also maintain the bastion approach, not least as a backup option. Many analysts seem to think that Beijing currently favors the option of deploying SSBNs in the more protective setting of bastions in its coastal waters as an alternative to open-ocean patrols. Many U.S. and Chinese analysts speculate that China is mirroring the Soviet practice from the 1970s and 1980s of creating such a bastion in part of the South China Sea to protect its SSBNs.27 Despite some potential challenges, it appears that Chinese experts generally agree that the bastion strategy is a reasonable one for Beijing to adopt, especially in parts of the South China Sea. Given the large submarine base China has built near Sanya on Hainan Island, Beijing clearly intends to use the South China Sea as an important operational area for its SSBN fleet.

Although the government has not officially used the term bastion, Chinese military analysts have widely assumed that the state is systematically implementing this strategy. Indeed, there are clear advantages to this approach. The northern and central parts of the South China Sea are deep enough for large nuclear submarines to operate. The temperature and salinity of the water there create natural barriers for sound propagation and submarine detection. The presence of busy civilian shipping lanes further complicates the underwater sound environment and helps Chinese SSBNs avoid detection. Moreover, Chinese SSBNs in the South China Sea can readily receive surface and aerial protection from China’s South Sea Fleet and other general-purpose forces. China’s growing power projection capability and newly built dual-use infrastructure on Hainan, the Paracel Islands, and the Spratly Islands are further advancing its capacity to protect SSBNs deployed in nearby waters.

Aside from the South China Sea, it is possible that China’s SSBNs may also use parts of the Yellow Sea and the East China Sea as secondary patrol areas. China has an important submarine base near Qingdao in Shandong Province, and satellites have often spotted Chinese nuclear submarines, including SSBNs, in its vicinity.28 Although the relatively shallow waters of the Yellow and the East China Seas are not ideal for nuclear submarines, operating SSBNs from these waters would make their locations less predictable and prevent the United States from concentrating its strategic ASW efforts in one area.29

Many analysts seem to think that Beijing currently favors the option of deploying SSBNs in the more protective setting of bastions in its coastal waters as an alternative to open-ocean patrols.

A bastion strategy also has logistical advantages over open-ocean patrols. Chinese SSBNs operating in bastions do not need to make long transits from their home ports to reach patrol areas in coastal waters, greatly reducing the risks to SSBNs in transit. In addition, the proximity of patrol areas to the mainland and the presence of friendly platforms considerably simplify the challenges of maintaining effective and reliable command, control, and communications arrangements. Moreover, deploying SSBNs in coastal waters would simplify logistics, especially resupply, during a protracted crisis. If an SSBN required critical supplies while on patrol in coastal waters, it could be serviced by surface ships or aircraft without sailing back to a port. This vertical form of resupply could be accomplished rapidly and would enable the SSBN to remain on patrol continuously.30 By contrast, Chinese capabilities to provide similarly effective logistical support to vast areas of the Pacific will likely remain limited, at least for the time being.

In spite of these advantages, there are important challenges to the effectiveness of Beijing’s bastion strategy—challenges that Moscow did not face when it employed a similar tactic. First, the limited range of the JL-2 SLBM reduces the deterrent value of basing SSBNs in Chinese coastal waters. While the JL-2 may be able to strike Guam or Hawaii from such waters, it could not strike the continental United States. As a result, in a serious crisis, China might well decide to send its SSBNs out to the Western Pacific to bring the U.S. mainland within range.

Second, China’s most likely SSBN bastions would be located in far more crowded waters. Unlike the areas where the Soviet Union (and later, Russia) set up its submarine bastions—in relatively isolated coastal waters, such as the Sea of Okhotsk and the Kara Sea—there is extensive commercial shipping in the South China, East China, and Yellow Seas. Moreover, the South China Sea, in particular, is surrounded by a number of other countries, making it likely that foreign navies would be present during both peacetime and a crisis. The relatively complex underwater sound environment in the South China Sea makes China’s submarines easier to hide, but this property also makes it more difficult for China to identify and repel foreign attack submarines.

A further complication is that the United States and its allies have critical sea lines of communication (SLOCs) located in the South China Sea—the same area where China is most likely to build its SSBN bastion. The United States and its allies, therefore, have strong incentives to deploy attack submarines and other assets to this area to protect these SLOCs. Especially in a crisis or conflict, such attack submarines would inevitably pose a direct threat to Chinese SSBNs operating in the same area, even if the United States did not intend for them to. By contrast, during the Cold War, the SLOCs most important to the United States and its NATO allies were in the North Atlantic Ocean, far to the south of the main Soviet SSBN bastions in the Barents Sea. In short, China faces challenges in protecting its SSBN bastion that the Soviet Union did not.

One final factor China must consider is U.S. missile defenses in the region. The recent deployment to South Korea of an AN/TPY-2 radar—as part of the Terminal High Altitude Area Defense (THAAD) system—has heightened China’s concerns about the U.S. missile defense network in the Asia Pacific.31 Chinese SLBMs launched from the country’s coastal waters—whether JL-2 SLBMs aimed at regional targets or future JL-3 SLBMs aimed at the U.S. homeland—might be a little easier for Washington to intercept than missiles launched from the vast Pacific Ocean. In the case of SSBNs located in coastal waters, the United States would know the general area from which a Chinese SLBM might be launched and could concentrate radars and other sensors there to ensure timely detection and accurate tracking. The United States already has two AN/TPY-2 radars deployed in Japan, in addition to the one in South Korea. These assets could help detect and track Chinese SLBMs launched from Bohai Bay, the Yellow Sea, and the East China Sea.32 Meanwhile, the PAVE PAWS early warning radar in Taiwan could help detect SLBMs launched from the South China Sea.33 Taiwan denies that it shares the radar data with the United States, but Chinese analysts are skeptical of this claim.

It can be safely assumed that China’s best short-term option for now is to continue operationalizing a bastion strategy for its SSBNs in its coastal waters.

To complement these land-based missile defense assets, Washington also has a surge capability to deploy a large number of Aegis-equipped ships armed with SM-3 ballistic missile interceptors to China’s coastal waters in a crisis. For some time, the United States had intended to develop a variant of the SM-3 interceptor capable of conducting ascent-phase interception against some ICBMs or SLBMs.34 Although the Obama administration in 2013 canceled the development of this interceptor, the SM-3 IIB, some Chinese assessments have concluded that the SM-3 IIA interceptor (which is expected to be deployed shortly) might be capable of intercepting Chinese SLBMs launched from China’s coastal waters.35

These potential challenges to the survivability of Chinese SSBNs and SLBMs even in coastal waters notwithstanding, it can be safely assumed that China’s best short-term option for now is to continue operationalizing a bastion strategy for its SSBNs in its coastal waters. This approach, while not officially announced, likely will continue to form the backbone of China’s sea-based nuclear deterrence strategy, at least until some undetermined point in the future when Chinese SSBNs are deemed much more survivable on their own.

Notes

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

2 Wu, “Survivability of China's Sea-Based Nuclear Forces.”

3 Yang Lianxin (杨连新), “The Four Stages of China’s Nuclear Submarine Development” [中国核潜艇创业发展的 ‘四个阶段’], China Nuclear Industry (中国核工业) 11 (2013): 57–60.

4 Shi Yang (施洋) and Xi Yazhou (席亚洲), “Farewell, the Childhood of China’s Nuclear Submarines [别了, 中国核潜艇的 ‘少年时代’], Military Industry Culture (军工文化), no. 11 (2013).

5 “Suspected Newest 094a Strategic Nuclear Submarine of the Chinese Navy Was Revealed” [疑似中国海军最新094a战略核潜艇首次曝光], Sina Military, http://mil.news.sina.com.cn/china/2016-07-05/doc-ifxtsatn8121274.shtml; “The Mainland’s New 094a Nuclear Submarine Revealed for the First Time” [陆新型094a核潜艇首曝光], China Times (中时电子报), July 05, 2016.

6 Wu, “Survivability of China’s Sea-Based Nuclear Forces”; and Tian Jianwei (田剑威), “094 Nuclear Submarine: China’s ‘King of South China Sea’” [094 型核潜艇, 中国 ‘南海之王’], Communists (共产党员) 8 (2014): 60–61.

7 Lan Bai (蓝白), Dong Ming (东名), and Wen Cheng (闻成), “Divergent Views Over Strategic Nuclear Submarine Development” [战略核潜艇发展分歧], Ordnance Knowledge (兵器知识), no. 1 (2012).

8 Sheng Danling (盛丹凌) and Chen Yongyao (陈永耀), “Stealth Requirements for China’s Submarines” [中国潜艇的隐身需求], Naval & Merchant Ships (舰船知识), no. 5, 2013.

9 “Foreign Media: China Sent Its Nuclear Submarine for First Combat Patrol” [外媒:中国派遣核潜艇进行首次战斗巡航], Reference News, (参考消息).

10 Shi and Xi, “Farewell, the Childhood of China’s Nuclear Submarine” [别了, 中国核潜艇的 “少年时代].

11 Wu Riqiang, “SSBNs Are Unnecessary and Destabilising,” The Interpreter (blog), Lowy Institute, August 7, 2014.

12 Wang Yifeng (王逸峰) and Ye Jing (叶景), “Lessons for China’s Nuclear Submarine Penetration From the Sino-Japanese Nuclear Submarine Incident” [从中日核潜艇事件看我核潜艇的突防], Shipboard Weapons (舰载武器), no. 3 (2005).

13 “CCTV Exclusive Interview With Academician Ma: China’s New Nuclear Submarine Electronic System More Advanced Than the US” [央视专访马伟明院士:中国新核潜艇电力系统领先美国], Sina Video, May 31, 2017, http://video.sina.cn/news/2017-05-31/detail-ifyfqqyh9093246.d.html?cre=wappage&mod=r&loc=3&r=9&doct=0&rfunc=0&tj=none&s=0.

14 Brooks, “Strategic Stability and Submarine Operations: Lessons From the Cold War.”

15 Bryan Clark, “The Emerging Era in Undersea Warfare,” Center for Strategic and Budgetary Assessments, 2014; Walter M. Kreitler, “The Close Aboard Bastion: A Soviet Ballistic Missile Submarine Deployment Strategy,” Naval Postgraduate School, 1988.

16 Du Debin (杜德斌), Ma Yahua (马亚华), Fan Fei (范斐), and Yun Caixing (恽才兴), “China’s Maritime Transportation Security and Its Safeguard Measures” [中国海上通道安全及保障思路研究], World Regional Studies 24, no. 2 (2015):1–10; Hu Jinyang (胡锦洋), “The Julang Sweeping Through West Pacific Ocean” [‘巨浪’ 席卷西太平洋], Aeronautical Knowledge (航空知识) 1 (2014): 49–51; Shi Qin (矢勤), “History of Ballistic Missile Nuclear Submarine Operational Patrols” [弹道导弹核潜艇战备巡航史], Modern Ships (现代舰船) 2 (2016): 37–42; and Wen Tao (文涛), “How China’s Nuclear Submarines Can Effectively Deter the United States” [中国核潜艇如何有效威慑美国], Modern Ships (现代舰船) 19 (2015): 30–42.

17 Ji Shuangcheng (纪双城) et al., “UK Media Said Chinese Strategic Nuclear Submarine Will Patrol the Pacific and Chinese Experts Respond: No Need to Be Surprised” [英媒称中国战略核潜艇将巡航太平洋 中方专家:无须惊奇], Global Times (环球时报), May 28, 2016; and Qiu, “Risk Still Exists for Our Nuclear Submarine Far Sea Patrols: Two Methods to Break Through Island Chain” [我国核潜艇远洋巡航仍存风险 两种方式可穿越岛链].

18 Office of the Secretary of Defense, Annual Report to Congress: Military and Security Developments Involving the People's Republic of China 2016.

19 Daniel Coats, “Worldwide Threat Assessment of the U.S. Intelligence Community,” Office of the Director of National Intelligence, February 13, 2018.

20 Xia Yinshan (夏银山), “Analysis of Key Technologies Development of Foreign Nuclear Submarines” [国外核潜艇关键技术发展研究], Ship Science and Technology (舰船科学技术) 25, no. 4 (2003); and Yang, “Ballistic Missile Nuclear Submarine and National Security” [弹道导弹核潜艇与国家安全].

21 Robert Waring Herrick, “Pro-SSBN Mission: The SSBN-Protection Mission Part II, Final Report Soviet Naval Mission Assignments,” Ketron, Inc., July 12, 1979.

22 Zhang Jiexian (张洁娴), “Chinese Naval Exercise Trailed by Japanese Ships; China’s Surveillance Against the Ships Was Protested Unexpectedly” [中国海军演练遭日舰跟踪 我对其侦察反遭抗议], People.cn (人民网), http://mil.huanqiu.com/observation/2012-10/3179918.html.

23 See, for example, Li Xiaokun, “China Sails Through ‘First Island Chain,’” China Daily, August 2, 2013.

24 Wen, “How China’s Nuclear Submarines Can Effectively Deter the United States” [中国核潜艇如何有效威慑美国].

25 “Domestically-Made Aircraft Carrier Will Still Use Ski-Jump Take-off: Main Mission Is to Cover Nuclear Submarine at Sea” [国产航母仍为滑跃起飞:主要任务是掩护核潜艇出海], Sohu Military, 2015.

26 Ronald O’Rourke, “China Naval Modernization: Implications for U.S. Navy Capabilities—Background and Issues for Congress”; Christopher H. Sharman, “China Moves Out: Stepping Stones Toward a New Maritime Strategy” National Defense University Institute for National Strategic Studies Center for the Study of Chinese Military Affairs, 2015.

27 David S. McDonough, “Unveiled: China’s New Naval Base in the South China Sea,” National Interest, March 20, 2015; Li Xun (李寻), “South China Sea: New ‘Bastion’ for China’s Nuclear Submarine?” [南海:中国核潜艇新‘堡垒区’?) China National Defense News (中国国防报), September 27, 2011.

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

29 Christopher Mcconnaughy, "China’s Undersea Nuclear Deterrent: Will the U.S. Navy Be Ready?,” in China’s Nuclear Force Modernization, ed. Lyle J. Goldstein and Andrew S. Erickson (Newport, Rhode Island: Naval War College Center for Naval Warfare Studies, 2005).

30 Kreitler, “The Close Aboard Bastion: A Soviet Ballistic Missile Submarine Deployment Strategy.”

31 Wu Riqiang, “South Korea’s THAAD: Impact on China’s Nuclear Deterrent,” Nanyang Technological University S. Rajaratnam School of International Studies, July 27, 2016.

32 Wu Riqiang, “U.S. to Deploy THAAD in South Korea: Implications for China’s National Security” [美国要在韩国部署 ‘萨德’, 对中国国家安全会有哪些影响?], Tengxun Jiangwutang (腾讯讲武堂), 2014, http://www.globalview.cn/html/military/info_9055.html.

33 “Japanese Newspaper Analyzes East Asia Ballistic Missile Defense Posture Against China” [日刊解析针对中国的东亚弹道导弹防御态势], Reference News (参考消息), May 3, 2015.

34 Thomas Karako, “Aegis Intercept Test: Critical Questions,” Center for Strategic and International Studies Missile Defense Project, June 22, 2017.

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