China finally achieved an operational underwater nuclear capability in recent years, almost six decades after it first launched its nuclear-powered ballistic missile submarine (SSBN) program in the late 1950s. The deployment of the Jin-class (Type 094) SSBNs armed with JL-2 submarine-launched ballistic missiles (SLBMs) marks a new stage in the evolution of China’s sea-based nuclear force. According to the Pentagon’s 2018 annual report ^[1] to Congress on China’s military capabilities, this recent development constitutes ‘China’s first credible sea-based nuclear deterrent’.

However, the effectiveness of China’s current sea-based nuclear force still faces serious challenges from geographic, operational and technological factors. But if China develops a larger and more invulnerable SSBN capability, incorporating continuous at-sea deterrence (CASD), how would this build-up affect strategic stability in the Indo-Pacific?

Driven by Beijing’s perceived nuclear insecurity, and enabled by the availability of resources to the People’s Liberation Army, China’s SSBN fleet, SLBM program, and supporting capabilities and systems have developed quickly since the early 2000s. Chinese military experts ^[2] believe that developing an effective sea-based nuclear force is critical for ensuring the credibility of China’s overall nuclear deterrent.

The steady growth in the size and sophistication of China’s SSBN fleet will continue. Indeed, by all indications, a larger and more survivable SSBN force is high on the PLA Navy’s list of priorities.

China had at least four ^[3] operational Jin-class SSBNs in 2018, and two more have reportedly ^[4] just joined the fleet. The PLA Navy will likely build a total of six to eight Jin-class SSBNs before shifting production towards its next (third) generation SSBN, the Type 096, from the early 2020s. From the mid- to late 2020s onwards, it will likely operate an SSBN fleet consisting of both the Type 094 and Type 096.

The future of China’s SSBN force depends largely on China’s threat perception. At one end of the spectrum, Beijing may believe that a small SSBN fleet that complements its land-based nuclear force is enough to maintain the credibility of its nuclear deterrent. On the other end, China may seek to address perceived vulnerabilities in its land-based force with a significant build-up of its SSBN force with supporting infrastructure and systems.

Another important determinant is whether China intends to pursue a CASD capability with one or more SSBNs on patrol at all times. China is unlikely to adopt such a posture in the near term due to operational constraints. Even if the PLA Navy was operationally capable, there are serious doubts as to whether Beijing is ready to make such a major shift in its nuclear posture.

The precise number of SSBNs required for CASD would depend on a variety of factors, including the efficiency of the PLA Navy’s logistics support for its SSBN fleet, and the technical specifications of Chinese nuclear reactor cores. But if Beijing’s aim is to achieve CASD with at least two or three SSBNs on patrol at all times, China’s SSBN force will need to expand ^[5] to around 12.

The growth of China’s SSBN fleet, as part of its broader nuclear modernisation effort, has a number of implications for China’s nuclear strategy and strategic stability in Asia. First and foremost, China’s SSBN force has become more important to its nuclear strategy and posture than at any time in the past. With the diversification away from an exclusive reliance on land-based nuclear missiles, SLBMs have grown ^[6] to constitute about half of China’s total number of ballistic missiles that could target the continental US.

This relative importance is likely to grow along with the size and survivability of China’s SSBN fleet as China progresses along the path towards building an effective nuclear triad. Currently, China possesses a well-established, albeit relatively small, land-based nuclear force, a nascent sea-based nuclear force, and a program to develop a new strategic bomber, the H-20.

Given the growing importance of China’s SSBNs, decisions about how they’re deployed may have far-reaching strategic implications. For instance, if Beijing decided to adopt CASD, that would constitute an important shift in China’s nuclear posture. Currently, nuclear authority is highly centralised ^[7] under the Central Military Commission, with nuclear warheads stored separately from missile launchers. In addition, China’s land-based nuclear force doesn’t maintain a high alert status under normal peacetime conditions.

With CASD, patrolling Chinese SSBNs would carry nuclear weapons to sea, and Beijing would need to work out crucial command and control questions ^[8], such as how much authority to delegate to submarine commanders. Such a shift in posture might be interpreted by other states as evidence that Beijing was moving away from its policy to refrain from the first use of nuclear weapons.

In the short to medium term, the PLA Navy will continue to adopt a strategy that heavily emphasises SSBN deployments to selected ‘bastions’ near the Chinese mainland, including areas of the South China Sea, East China Sea and Yellow Sea. However, over the longer term, Chinese SSBNs are likely to be increasingly active in conducting open-ocean patrols in the Pacific Ocean.

Given the advantages of open-ocean deployment, the PLA Navy will continue to develop the capabilities and experience required for effective deterrence patrols, especially in the Pacific Ocean.

A key risk to strategic stability is that Beijing’s self-perceived defensive build-up could be interpreted by the US and others as aggressive efforts aimed at altering the relative strategic balance of force in China’s favour. This would be especially likely if Beijing rushes to adopt CASD in the near future.

This piece was produced as part of the Indo-Pacific Strategy: Undersea Deterrence Project ^[9], undertaken by the ANU National Security College ^[10]. This article is a shortened version of chapter 8, ‘The future of China’s new SSBN force’ ^[11], as published in the 2020 edited volume The future of the undersea deterrent: a global survey ^[12]. Support for this project was provided by a grant from Carnegie Corporation of New York.