Tag Archive for: Undersea deterrence

Nuclear-armed submarines and strategic stability in the Indo-Pacific

No other weapon system embodies the menacing, but also out-of-sight, presence of nuclear weapons better than the stealthy nuclear-powered ballistic missile submarines (SSBNs) that have, for six decades, ceaselessly prowled the world’s cold ocean depths, waiting for an order that has never come. SSBNs on continuous at-sea deterrence missions remain the mainstay of the nuclear forces in the United States and France, and the sole platform carrying British nuclear weapons. Despite Russia’s significant investment in road-mobile missiles, SSBNs also remain an important element of its nuclear forces.

In Asia, however, nuclear-armed submarines are a newer phenomenon. China has had a longstanding interest in developing SSBN technology, but has only in recent years put them into service, in numbers comparable to Britain’s and France’s. Israel has reportedly fielded nuclear-armed (cruise) missiles on its conventionally powered submarines, and India, Pakistan and North Korea have also all shown an interest in moving nuclear weapons under the sea. As these countries’ programs mature, undersea nuclear deterrence will cease to be a preserve of the major powers. The relevance of nuclear-armed submarines for strategic stability in the Indo-Pacific area will thus increase—but what will their impact be?

A common idea in the international commentariat on nuclear weapons and international affairs is that strategic stability could be ‘assured’ by ‘mutually assured destruction’, based on a relatively small number of large-yield, survivable warheads, such as those carried on an SSBN. But while using submarines to strike the land promises survivable nuclear forces, it also provides long reach and the ability to conduct surprise attacks with short warning, and from unexpected angles—factors much less prone to promote stability. Indeed, the latter two considerations were particularly important for the development and geographic deployment of SSBNs during the Cold War, especially by the Soviet Union. They may be so again as countries in Asia look to overcome the missile defence capabilities fielded by the United States and its allies.

The survivability of SSBNs has also recently been called into question by many commentators, especially in the debates on the replacement of the Trident nuclear submarines in the United Kingdom. A confluence of new technologies, such as unmanned vehicles and big-data analytics, with improved sonar, signals and imagery sensors, and the potential for completely new sensing technologies based on, for example, quantum effects, may render the oceans ‘transparent’ to anti-submarine forces.

The historical record on the vulnerability of SSBNs is already more ambiguous than often acknowledged in these debates. Technology is but one factor influencing the survivability of SSBNs, which has historically differed widely for different countries based on their geographic situation and adversary capabilities.

During the Cold War, the US developed long-range passive sonar systems that could track specific tonal frequencies of Soviet submarines in the North Atlantic and Pacific oceans. These systems made Soviet undersea capabilities far more vulnerable than realised by the public at the time and, until the 1970s, even by the Soviet Union. Insofar as there was an undersea ‘arms race’, it occurred not between adversaries’ nuclear forces, but between Soviet SSBNs and US anti-submarine warfare (ASW) forces.

In this and future contests, geography remains a central factor, because it conditions the ability of countries to make use of (or counter) new ASW technologies that might increase the risk to SSBNs. Moreover, only the US and Russia openly seek the ability to hold other countries’ nuclear forces at risk as part of their deterrence posture, and hence have an operational need to counter adversary SSBNs.

There are also other ways of protecting SSBNs than relying on stealth alone. Once the Soviet Union realised that its SSBNs were vulnerable and that the range of its submarine-launched missiles allowed it to target the continental US from the Arctic Ocean, it began to confine its SSBN deployments to ‘bastions’ in the Barents Sea and Sea of Okhotsk that were actively defended against allied submarines by the Soviet navy and by land-based aircraft.

But if the survival of SSBNs depends not on stealth but on one’s own defensive ASW capabilities to protect them from adversary hunter–killer submarines, the implications of radical improvements in ASW for SSBN survivability and crisis stability also become less clear-cut. Indeed, this dynamic may in fact make SSBNs more survivable, not less—if at the cost of significant investment in defensive ASW forces—such as that which we might now see underway by China in the South China Sea.

Whether the increased deployment of SSBNs in the Indo-Pacific will thus be stabilising or destabilising—in arms competition as well as in crises and war—remains an open and important question for regional security. Given the multiple centres of power in the Indo-Pacific, its connected conflict dyads, and its regional order that lacks both the informal rules and clear dividing lines of the Cold War, conceiving of a regional concept for ‘stability’ is fraught in general.

When assessing the current and future impacts of SSBN technology and deployments on strategic stability in the Indo-Pacific, we thus need to look beyond superficial readings of Cold War history that equate SSBN forces with a supposedly stabilising way of deploying nuclear forces as a secure second-strike capability—for they may be neither intended for second strike, nor particularly secure.

Rather than being a technologically deterministic relationship, the consequences of changes in ASW technology and of the deployment of SSBNs in the region will reflect the particular geographic and strategic circumstances of each adversarial dyad, and defy easy generalisation.

This piece was produced as part of the Indo-Pacific Strategy: Undersea Deterrence Project, undertaken by the ANU National Security College. This article is a shortened version of chapter 3, ‘SSBN, nuclear strategy and strategic stability’, as published in the 2020 edited volume The future of the undersea deterrent: a global survey. Support for this project was provided by a grant from Carnegie Corporation of New York.

The role of nuclear weapons in China’s national defence

At the end of April, two upgraded Chinese Type-094 nuclear-powered ballistic missile submarines (SSBNs) reportedly went into service. But China’s SSBN capability is a far less important component of its nuclear deterrent than its land-based missile force. And that nuclear deterrent plays an important but limited role in China’s national defence. Absent major strategic change, the role of nuclear weapons in China’s national defence strategy is unlikely to expand. And absent major technological change, the relative importance of China’s sea-based deterrent is also unlikely to grow.

Although the commander of US Strategic Command, Admiral Charles A. Richard, recently stated that he could ‘drive a truck through China’s nuclear no first use policy’, that policy has played a critical role in China’s nuclear force development since 1964. China’s nuclear force structure is optimised to ride out an adversary’s nuclear strike and then retaliate against an adversary’s strategic targets, rather than credibly threaten first use. China’s operational doctrine for its nuclear forces doesn’t include plans for the first use, or threat of first use, of nuclear weapons in a conventional conflict. While Chinese leaders and strategists have debated changes to the no-first-use policy from time to time, there’s no sign that China plans to abandon it. The policy was most recently reaffirmed in China’s 2019 defence white paper.

China’s top leaders in the politburo and Central Military Commission exercise strict control over both the formulation of nuclear strategy and the authority to alert or use nuclear weapons. To ensure they’re not used accidentally, mistakenly or without authorisation, nuclear weapons are kept off alert in peacetime and warheads are stored separately from delivery systems in a central depot deep in the country’s interior.

There are two potential changes to the threat environment that could prompt Beijing to rethink its restrained nuclear posture: a dramatic increase in the intensity of the US threat China faces and a radical technological change that weakens its retaliatory-only policy.

If Chinese leaders concluded that a future conflict with the US posed an existential threat rather than a limited war, they could look to nuclear weapons as insurance against a conventional defeat that eliminated the Chinese state. But such a change is by no means a given. Chinese strategists stress a number of reasons for the country’s restrained nuclear strategy, including the difficulty of controlling nuclear escalation and geography. China’s large size provides it with non-nuclear options for defeating a conventional military threatening its survival. An increase in US hostility wouldn’t remove these incentives for restraint.

A breakthrough in the development of counterforce technology is also unlikely to change China’s retaliatory nuclear posture, unless it were so radical that it made that posture unviable. Those changes would have to enable the US to credibly threaten to destroy most of China’s retaliatory force. It would also have to render China’s other options for ensuring a survivable nuclear force futile, such as expanding its arsenal size or shifting to a launch-on-warning alert status. Such radical technological change is unlikely, despite persistent US efforts to improve its counterforce capabilities.

Regardless of whether either of these situations come to pass, China’s land-based missile force is unlikely to be displaced by its sea-based deterrent as the primary leg of its retaliatory nuclear capability, for four reasons.

First, Chinese strategists acknowledge the shortcomings of the current generation of Type-094 submarines, which are noisy and therefore vulnerable to sophisticated US strategic anti-submarine warfare (ASW) capabilities. China could overcome these technological hurdles in the future, although it would be racing against simultaneous American ASW improvements—something the US has proven adept at throughout and since the Cold War.

Second, and regardless of its technological progress, China does not (yet) appear to have invested in its own strategic ASW forces. It may therefore lack confidence that SSBNs patrolling in the open ocean could evade detection by US ASW capabilities. Protecting SSBNs using the PLA Navy’s conventional forces is another option, but would come at an opportunity cost for other naval missions.

Third, China’s geography makes its SSBNs more vulnerable to ASW than those of the US and other naval nuclear powers because they must pass through chokepoints in the first island chain to enter the Western Pacific. The territory bordering those chokepoints belongs to US allies and partners, who may assist US ASW with shore-based signals processing. No technical improvements to Chinese submarines are likely to be able to overcome the disadvantages posed by its geography.

Fourth, developing operational doctrine for SSBNs poses distinctive challenges to strict control of top Chinese leaders over the use of nuclear weapons. Those leaders may not be comfortable with pre-delegating authority to use nuclear weapons to submarine commanders if communications are severed, or mating nuclear warheads and missiles in peacetime. Yet without these two amendments to its nuclear operations, which is optimised for the land-based force, China may not be able to reap the full benefits of deploying an SSBN force for securing a second-strike capability.

Given these constraints, why, then, has China continued to develop a sea-based nuclear deterrent?

Speculatively, a mix of hedging and organisational interests of the PLA Navy is the most likely explanation. SSBNs may help China to hedge against improvements in US missile defence focused on intercepting missiles launched from the Chinese mainland.

Although China’s SSBN force is unlikely to become central to securing its second-strike capability, it could have a strong influence on US–China strategic stability.

In addition to the use-or-lose pressures resulting from operating a vulnerable SSBN force in a crisis, SSBNs could undermine confidence in China’s nuclear restraint. If Chinese leaders decide to change their warhead handling practices, or pre-delegate nuclear launch authority, they will change longstanding practices for China’s nuclear operations. As China formulates operational doctrine for its SSBN force, it should carefully consider the value of existing nuclear practices as signals of restraint.

This piece was produced as part of the Indo-Pacific Strategy: Undersea Deterrence Project, undertaken by the ANU National Security College. This article is a shortened version of chapter 7, ‘The role of nuclear weapons in China’s national defence’, as published in the 2020 edited volume The future of the undersea deterrent: a global survey. Support for this project was provided by a grant from Carnegie Corporation of New York.

Nuclear-armed submarines and the balance of power in the Indo-Pacific

The maritime strategic balance in the Indo-Pacific is changing rapidly. The future of undersea nuclear deterrent forces has strategic, operational and force structure aspects for all major powers in the region. Strategic competition in an increasingly competitive environment has a significant maritime element, which itself is profoundly influenced by the continuing importance—and progressive expansion—of the region’s underwater nuclear deterrent forces.

To a greater extent than during the Cold War, both threatening and protecting such assets will be difficult to separate from other maritime campaigns. This particularly applies to potential anti-submarine warfare (ASW) operations in the East and South China Seas, as well as to India and Pakistan and to North Korea, creating uncertainty over the possibility of unplanned escalations and outright accidents.

Maintaining any kind of regional balance will, therefore, call for cool judgements on the part of all the players, judgements that will need to be continually revised in the light of technological innovation and force development.

The US Navy’s nuclear-powered ballistic missile submarine (SSBN) force is central to the country’s nuclear arsenal. While the navy can’t be complacent about threats to the survivability of its submarines, until there are revolutionary developments in sensor technology, the combination of geography, oceanography, and platform and missile capabilities means that its at-sea deterrent will remain the most secure element of America’s nuclear force and thus receive high priority in funding.

The problem for the US Navy is that it will need to start replacing the Ohio class within the next decade, but the cost of 12 new Columbia-class submarines will severely limit its ability to regenerate all the other force elements that will be required to meet the combined challenges of China and Russia.

The navy’s efforts represent just one part of a strategy to push the US’s competitors off balance and regain the strategic initiative. An important maritime element is likely to be undermining China’s efforts to create an underwater ‘bastion’. Here, the Americans must weigh the benefits of actively threatening the security of the People’s Liberation Army Navy’s SSBN force against the resource commitments that that would entail, as well as the complications that it could represent for alliance arrangements, notably with Japan and Australia.

In seeking to become the predominant maritime power in the western Pacific, China has its own problems of resources and technology. However attractive the concept of an at-sea deterrent force within its nuclear inventory may be, China must first extend the range of its submarine-launched missiles and considerably improve the stealth qualities of its missile submarines if it is to create a capability sufficient to pose a credible threat to the continental United States.

Russia’s challenges are in some ways parallel to those of the US, particularly its need to sustain an SSBN force while modernising the remainder of its navy. Maintaining an at-sea nuclear deterrent remains the highest priority. However, replacement of the older SSBN with the new Borey class must be consuming a very large share of the Russian navy’s resources. To the SSBN program must be added the need to renew the nuclear-powered attack submarine force and continue development of the ASW capabilities necessary to secure the bastions against potential attackers. The limited money available means that Russia’s maritime power-projection assets don’t enjoy the same level of attention.

Japan’s defence expansion, despite the tensions with China and the rise of the PLA Navy, has been relatively limited. Its most significant new elements are focused on developing amphibious forces capable of responding rapidly to any threat to the Ryukyu Islands, including the contested Senkaku (Diaoyu) Islands. Japan’s ASW efforts are much less visible in, but perhaps more significant for, its maritime strategy. Japan’s submarine force is slowly expanding, and the modernisation of its surface and air ASW forces continues.

Australia faces equivalent challenges. Because it is one of the few regional players with substantial high-technology capabilities, particularly in the ASW domain, Australia’s assistance will be eagerly sought by the Americans, just as they have long looked to Japan. While its defence expansion remains relatively constrained—and slow—Australia’s emerging force structure will provide both independent national capabilities and strategic weight in alliance terms in ways that are relatively new. Australia has been a regular presence in the South China Sea over many years, but the latest Indo-Pacific Endeavour task group deployments have been on a larger scale than the individual ship deployments of the recent past.

North Korea remains a wild card. Its efforts to develop an underwater nuclear deterrent are only a small part of the increasingly complex problem its future presents for neighbouring countries and the region as a whole.

India must balance its apparently unresolvable tensions with Pakistan against a developing strategic rivalry with China that has important maritime dimensions. The growing Chinese economic and military presence in the Indian Ocean threatens India’s self-image as the dominant power in the region. India’s interest in the South China Sea represents something of a riposte and a deliberate effort to complicate China’s maritime strategy.

On the other hand, the entry of the first Indian SSBN into operational service and the start of its deterrent patrols may have added to India’s nuclear capabilities, but they also create a hostage to fortune that the Indian Navy must factor into its dispositions. Whether Pakistan will add to India’s problems by embarking nuclear weapons in its submarine force is uncertain, as is the priority that the Pakistan Navy will give to locating and tracking Indian SSBNs.

In sum, strategic competition in the increasingly competitive Indo-Pacific has a significant maritime element. Distinguishing threatening and protecting nuclear assets from routine maritime campaigns is increasingly difficult. As SSBN capabilities proliferate, and ASW technology advances, maintaining a regional maritime balance will increase in complexity.

This piece was produced as part of the Indo-Pacific Strategy: Undersea Deterrence Project, undertaken by the ANU National Security College. This article is a shortened version of chapter 2, ‘Maritime and naval power in the Indo-Pacific’, as published in the 2020 edited volume The future of the undersea deterrent: a global survey. Support for this project was provided by a grant from Carnegie Corporation of New York.

Undersea deterrence and strategic competition in the Indo-Pacific

Amid rapid geopolitical change at the start of the 2020s, unfolding now in the Covid-19 crisis, nuclear weapons manifest grim continuity with the previous century. Especially persistent is a capability that has existed since the 1960s: the deployment of nuclear weapons on submarines. The ungainly acronym SSBN represents nuclear-powered ballistic missile submarines: the most destructive armaments carried on a supposedly undetectable, and thus invulnerable, platform. Over several articles, this series will illuminate new technologies and potential risks relating to undersea warfare and nuclear deterrence in the Indo-Pacific over a 20-year timeframe.

The various undersea nuclear deterrence programs in the Indo-Pacific region can’t be considered in isolation or solely in relation to one another. There’s a large and complex strategic context to the decisions by China, India, Pakistan and North Korea to invest in submarine-launched nuclear weapons programs, by the United States and Russia to modernise their own, and by the United States and its allies—notably Japan and Australia—to double down on their advantages in anti-submarine warfare.

Nuclear strategy can’t be divorced from multi-layered maritime competition involving everything from territorial disputes to resource exploitation to conventional naval operations. The contest for authority and control in the South China Sea isn’t simply about fish, energy resources, nationalism and history, but has a bearing on the balance of military power and prospects for coercion or deterrence in a crisis, right up to the nuclear level. Meanwhile, Chinese and American investments in disruptive technologies—such as quantum computing, artificial intelligence, autonomous systems and new sensing techniques—are part of a broader strategic competition related in part to deterrence in the maritime domain.

Serious complications arise, however, given the increased assertiveness of China’s wider strategic activity. Even if the Pentagon’s warnings of China’s hegemonistic ambitions are less than fully substantiated, it is clear that China under President Xi Jinping has set for itself strategic objectives that run counter to interests that other nations, and of course Taiwan, are willing to defend. Several of the region’s long-standing ‘flashpoints’ involve these clashes of interests, including territorial disputes in the South China Sea and in the East China Sea. The most obvious flashpoint involves Beijing’s insistence, enshrined in the so-called Anti-Secession Law, that it will use force to prevent Taiwan from formalising its independence.

Most of the many tensions that accompany China’s strategic assertiveness are in themselves unlikely to lead to armed conflict, let alone escalation to nuclear threats. In the South China Sea, Beijing has often been careful to rely on paramilitary coastguard units and militias to bully Vietnam and the Philippines, rather than resorting to direct application of naval force, but that may be changing. That said, Vietnam in particular has the emerging military capability to put Chinese forces at risk, at least in the early stages of a clash. More profoundly with regard to the nuclear issue, one credible explanation for China’s campaign of building and militarising islands in recent years has been its wish to secure control of the South China Sea to make that area an SSBN bastion. Disturbingly, the global shock of Covid-19 has barely interrupted China’s efforts to dominate the South China Sea.

In the East China Sea, China has for the moment backed away from high-risk confrontations with capable (and now reinforced) Japanese forces, not least following clarification that the US considers its security treaty to apply to clashes over the islands in question. In the Indian Ocean, it’s difficult to imagine a China–India confrontation—for instance, over the fate of a small island state such as the Maldives—escalating to war, although reports have surfaced that even the land-border clash at Doklam led Delhi to look for ways to remind Beijing of the nuclear factor. In North Asia, crisis scenarios involving the Korean peninsula could lead to US–China confrontation, but they could also lead to a degree of US–China cooperation, with the principal nuclear threat being the regime in Pyongyang, not each other.

In the end, however, the clearest prospect of armed confrontation between China and the US leading to nuclear threats continues to revolve around the status of Taiwan. There is a strategic logic to the PRC gaining military control over Taiwan, to break through China’s geographic constraint by way of the ‘island chains’ and secure access to the open Pacific. It would be an oversimplification to argue that a Taiwan crisis would escalate quickly to the nuclear level. There would be several ways for Chinese forces to initiate coercion, include economic blockade and cyberattacks. And the subsequent conflict could drag out on multiple levels, including international economic and diplomatic pressure on China.

Nonetheless, a Taiwan crisis—or indeed another conflict, such as one arising from a US–China skirmish in the South China Sea—could lead to a wider mobilisation of forces, including Chinese SSBNs and US and allied anti-submarine warfare assets, perhaps with nations pre-empting each other rather than necessarily planning to attack.

The role of China’s immature SSBN fleet in such a situation is unclear, but a few credible possibilities exist. It seems highly unlikely that China would threaten nuclear attack on Taiwan: it claims, after all, to be liberating its misguided compatriots. Nonetheless, wanting to reserve the right to retaliate to a future US nuclear attack, and thus seeking to discourage US conventional military intervention as well, Beijing could well choose to take precautions to protect its nuclear forces at an early stage. In the case of the SSBN fleet, this could involve putting boats to sea as soon as possible rather than keeping them inside their hardened ‘dens’ on Hainan.

Will future ‘game-changing’ detection technologies render the oceans transparent? Such a breakthrough threatens the assumption that SSBNs are invulnerable—core to the concept of strategic stability. Amid this uncertainty, it’s clear that undersea nuclear deterrence in the Indo-Pacific is increasingly complex, as both established and emerging players deploy more of their nuclear arsenals underwater. We know that strategy, geography and technology in relation to undersea nuclear deterrence had profound implications for stability during the Cold War, and can safely surmise that they will again in the future of the Indo-Pacific.

This piece was produced as part of the Indo-Pacific Strategy: Undersea Deterrence Project, undertaken by the ANU National Security College. This article is a shortened version of chapter 1, ‘Undersea deterrence and strategic competition in the Indo-Pacific’, as published in the 2020 edited volume The future of the undersea deterrent: a global survey. Support for this project was provided by a grant from Carnegie Corporation of New York.