Sea-based nuclear weapons and strategic stability

Admiral Sir Mark Stanhope (Ret.) is a former First Sea Lord and Chief of Naval Staff, Royal Navy. This is an extract from a presentation to a Lowy Institute international workshop on sea-launched nuclear weapons and strategic stability, held in Singapore earlier this year.

The role of nuclear ballistic missile submarines (SSBN) in strategic stability may seem obvious. However given developments in the Indo-Pacific, including progress in the Chinese and Indian SSBN programs, now is a good time to examine this scantly explored area. 

The SSBN HMAS Vanguard returning to HMNB Clyde, Scotland, 2010.

I have been asked to offer some insights from the Cold War and more generally from the British experience of operating an SSBN fleet.

It can be argued that the very existence of SSBNs, which provided a 'second-strike capability', was essential to the strategic stability achieved through nuclear deterrence in the Cold War. Before the introduction of SSBNs, the deterrence philosophy of 'mutually assured destruction' hinged on a 'launch on warning' mechanism, which involved both sides launching their nuclear weapons at the first sign of a detected nuclear strike.

Second-strike capabilities like the SSBN introduce the concept of a certainty of retaliation and eliminate the need for a launch on warning system, since any first strike is not capable of removing these 'invulnerable' weapons. Even when the 'Star Wars' missile defence debate was at its height in the early 1980s, the fundamental assurance of an invulnerable second-strike capability was not questioned.

But how invulnerable are these platforms today? [fold]

While science moves on at great pace and solutions for submarine detection are sought through non-acoustic means (for example, the use of satellites), sound in water remains the prime detection mechanism. All of us in the anti-submarine warfare world have been fighting with the physics of this since the advent of the submarine over 100 years ago.

It seems clear to me as a practitioner that noise quietening and signature reduction of nuclear propelled platforms remains the engineering challenge (and cost) that will continue to drive invulnerability. I consider it will continue to be so for some time yet.

Deterrence is about perception and an understanding by each side that there is a certainty of catastrophic retaliation. This certainty, when provided by the SSBN, is made up of a number of separate elements. The first consists of the technological capabilities of both the weapon system and the submarine supporting it. These include design, manufacture and build, engineering readiness, maintenance, sustainability, reliability and a continual need to demonstrate that it all works.

Then there is the human element, which includes not only the 'will' of politicians and state leaders to actually use the system, clearly a fundamental requirement of deterrence, but also the certainty of response by the people involved. This human element includes an enormous training load for everyone, including submarine crews, nuclear propulsion engineering support, missile and warhead maintenance staff and many more specialisations. There is also the need to foster an ethos in the delivery of the capability and to ensure the dedication of all those working within it. All of this places huge, unique and costly demands on the nation and workforce.

The practical realities and challenges of these technical and human issues cannot be over-emphasised. If the whole nuclear deterrence philosophy is about a perception of certainty, then it will only work if that certainty is underpinned by the professionalism needed to operate the SSBN and its nuclear weapons. 

The Cold War taught us that you have to work hard and spend a lot to maintain the invulnerability of the submarine platform and thereby the second-strike capability.

Assurance is required after each SSBN patrol that detection by the opposition has not taken place and that the submarine has retained the necessary material and personnel readiness to fire its missiles, if ordered, at any time during the patrol. Throughout the Cold War this readiness was measured in minutes.

Each patrol was (and still is) analysed in great depth using onboard recordings and other sources of intelligence to provide the necessary critical assessment of success. This after-action analysis makes a fundamental contribution to strategic stability and is also an important reassurance to political leaders.

I am not at liberty to talk much about the 'firing chain' of decision and authority, other than to highlight the importance of its structure — both in technical and human terms — to the credibility and accountability of deterrence. It has to be 100% secure from the actual issuing of orders themselves through to the assured communications link to the submarine and the missile-firing interface. And it needs practice and regular testing.

More broadly, it is no good simply training and exercising when working in the nuclear dimension. Absolute assurance of the safety and reliability of procedures and processes is necessary.

All nuclear activity is therefore underpinned by a quality control regime and constant qualification and re-qualification of operators. This fundamental requirement is a huge burden and takes considerable time, cost and effort. There are no shortcuts; it is a doctrine in and of itself and a considerable, but necessary, constraint. It needs to have built into it the reality that failure sometimes occurs, bringing with it the need for more time, training and examination. 

Lastly, getting a vulnerable 'when in base' SSBN to the deep sea, where it will become invulnerable, is a period of considerable risk. During the Cold War, this strategic vulnerability was principally overcome for the West and East through the adoption of the Continuous at Sea Deterrence philosophy or CASD. The idea of CASD has a built-in advantage for strategic stability. It is about the permanent presence of second-strike nuclear deterrence at sea. It has not been rushed to sea at a time of growing crisis, thereby aggravating and escalating a tense diplomatic environment. 

Of course it must also be recognised, with my Cold War comparison, that we were primarily in a bipolar deterrence environment, with simple binary statistics and capabilities that needed to be balanced. As nuclear states in Asia transition towards greater second-strike capabilities, they face the added challenge of multipolar nuclear deterrence, where confused messages may be worryingly easy to generate.

The Lowy Institute gratefully acknowledges support from the John D and Catherine T MacArthur Foundation for this Interpreter debate, which is part of a broader research, dialogue and outreach project on strategic stability in Indo-Pacific Asia.

Photo courtesy of Flickr user UK Ministry of Defence.

In this debate, both Thomas Mahnken and Elbridge Colby argue that a secure sea-based second-strike capability might embolden China to pursue a more aggressive foreign policy.

Their arguments are based on an article by Thomas Christensen, which drew the conclusion that China's nuclear strategy is based on a textbook of the PLA's Second Artillery Corps, Science of Second Artillery Campaigns, which calls for blurring the line between conventional and nuclear war.

Christensen's conclusion is problematic for several reasons.

First, the Second Artillery is responsible for implementing China's nuclear strategy, not making it. This is the responsibility of China's top political leadership.

Second, Christensen mistranslates a critical term and misunderstands the cultural context in which the textbook was written. Christensen interprets the terms of 'conventional war under nuclear deterrence', 'double deterrence' and 'nuclear forces as a shield for conventional forces' as if China would combine nuclear and conventional coercive means to achieve its diplomatic objectives. But the original meaning in Chinese is that if an adversary were to use nuclear forces as coercion against China in a conventional conflict, China would need its own nuclear capabilities to deter this potential coercion. [fold]

Rather than emboldening China to pursue a more aggressive foreign policy, a secure nuclear retaliatory capability will give China an equal footing in which to fight a conventional war with the US, where neither side could coerce the other with nuclear weapons. Recall that the direct driving factor of China's nuclear weapons program was the nuclear threats from America during the Korean War and Taiwan Crisis. China has already achieved mutual deterrence with America, and current China-US strategic relations are stable. However, US homeland missile defence has the potential to neutralise China's nuclear deterrent, and China may be forced to build up its nuclear arsenal in order to restore strategic stability.

Thomas Mahnken also mentioned the 'consequential' fact that China apparently, to some extent, co-mingles the deployment and command and control of its nuclear and conventional forces. While sharing his concern on possible escalation, two points have to be made.

First, China does operate both conventional and nuclear ballistic missiles, but China does not deliberately co-locate its conventional and nuclear missiles to confuse its adversary. Conventional and nuclear missiles require different operating sites, so technically it is not easy to co-locate them. Besides, co-locating different missiles to confuse the adversary would undermine the survivability of China's nuclear forces, which is not in China's interest.

Second, every country to some extent, including America, co-mingles the deployment and command and control of its nuclear and conventional forces. For example, America co-mingles the deployment of its SSNs and SSBNs, and US strategic bombers could be used for both conventional and nuclear purposes.

Potential China-US conflict escalation is a focus of current international relations scholarship. China is developing asymmetric means (in American terms, anti-access/area denial capabilities) to counter superior US military forces, and accordingly America is developing the Air-Sea Battle concept to address that. We should make it very clear that it is the interaction between these strategies that would cause escalation, rather than the strategies themselves. In order to understand the mechanism and try to reduce the escalatory risk, we need to analyze both sides' strategies and their interaction.

Simply blaming one side is not constructive and will not help.

Photo courtesy of Flickr user Chuck Hagel.

The central purpose of deploying strategic nuclear weapons on SSBNs, rather than on other less expensive and technologically demanding platforms, is to assure the survival of these weapons in order for them to conduct a second strike. The rationale is that assured retaliation will dissuade a potential adversary from attempting a preemptive decapitating strike, thus contributing to strategic stability.

Iskander Rehman questions the applicability of this logic in the context of South Asian regional nuclear dynamics and the Second Nuclear Age. From an Indian perspective, with flight times of missiles from estimated launch locations to possible targets being so short — just a few minutes — there is no chance of success for a 'Launch on Warning' policy. Having adopted a 'No First Use' policy, the survivability of India's retaliatory capability is crucial, which means it has little choice but to put a certain number of its missiles on SSBNs.

Nobody has made the case that Cold War policies and scenarios can be cut-and-pasted into the Indo-Pacific scene. But a credible second strike remains a deterrent for states contemplating a preemptive first strike as much in the Second Nuclear Age as during the Cold War, and it is certainly a stabilising factor. As one contributor to this debate has noted, land-based missile silos, launchers and airfields are more vulnerable than SSBNs, and this vulnerability creates instability by tempting a preemptive strike. [fold]

As with any policy, there are challenges. Some include command and control, doctrinal and strategic development, engineering, design and quieting, and attaining and maintaining professional excellence and operating standards. But it would be wrong to assume that these challenges cannot be met, and cite them as destabilising factors. 

Impact of nuclear cruise missiles on stability

In an earlier submission, I mentioned the potentially negative impact on strategic stability of cruise missiles being deployed at sea. This is for several reasons. One is that the platforms (naval vessels) are dual purpose, in that they are also used for normal fleet operations and are thus equipped with non-nuclear weapons. This creates opacity and uncertainty in cases of encounters at sea between potential adversaries in conditions of heightened tension. Secondly, although technical measures can be built in to prevent unauthorised or accidental launch (as is the case with US Navy Tomahawks), launchers and control systems for the cruise missiles are often stored with the main non-nuclear armament of the platform, and such technical measures are likely to remain unimplemented. And thirdly, if the case of the Nasr tactical nuclear missile launcher of the Pakistan Army is any indication, the command and control of Pakistan's nuclear armed-naval units will be with the commander of the unit. Thus, launch authority can be delegated to a tactical level, lowering the nuclear threshold dangerously.

Pakistani strategy

Pakistan's apparent strategy is to rely on battlefield nuclear weapons such as the Nasr to counter superior Indian ground forces. The maritime domain has been added to this strategy, with the planned deployment of the nuclear-capable Babur missile at sea, ostensibly to counter India's naval strength. This provocative and risk-prone strategy is one which Iskander Rehman has appositely called 'nuclear brinkmanship'. 

Range of India's missiles

A few participants have rightly pointed out the short range of the K-15, currently the only sub-launched missile in India's arsenal. Quite obviously, to be an effective deterrent, India's SSBN the INS Arihant and her successors will need to be armed with missiles of at least intermediate ballistic missile range (3,000 - 5,500km). Until a missile with this range becomes operational, India's sea-based deterrent must clearly be considered to be in a developmental stage.  

While the deployment of specific weapons does have a significant impact, there are other factors that contribute to nuclear stability. The most important of these is the stability and maturity of the states concerned in the management of this capability. The India-China situation is not one to cause unease in the sub-continent at the present time. It is the India-Pakistan situation that is cause for concern, primarily because of the overriding influence and control of the Pakistani military in that country's political and security affairs. The egregious stratagem adopted by Pakistan, euphemistically termed 'sub-conventional warfare', promotes terrorist attacks periodically across the border under a virtual nuclear umbrella, and keeps the both countries constantly on the brink. 

Nuclear stability is a spin-off from political stability and depends on the will of both parties in any dyad to eliminate nuclear risks; this would appear to be the fundamental problem at present.

Photo courtesy of Flickr user My Past.

From a strategic perspective, the bottom line attraction for states seeking to acquire nuclear ballistic missile submarines (SSBNs) is survivability. States possessing SSBNs cannot be victims of a disarming first strike.  They will always possess the ability to strike back with submarine launched ballistic missiles armed with nuclear weapons in order to inflict unacceptable damage on the attacking state. If this logic is correct, bilateral relationships will be stable because neither side will have an incentive to strike first.

Given some of the assertions in this Interpreter exchange on Indo-Pacific regional stability and SSBNs, it is worth revisiting two assumptions necessary to believe in SSBN survivability:

1. That they remain continuously at sea and;

2. They are very difficult to find once deployed.

Both assumptions are largely derived from the way the US and, to a lesser extent, the other powers possessing SSBNs — the British, French and Soviets — theorized about and operated SSBNs during the Cold War. [fold]

Yet for a SSBN force to operate continuously at sea requires at least three, but likely even more, of the platforms (depending on possible attrition during actual war) given deployment patterns. Neither India nor China are likely to possess sufficient numbers of SSBNs in the immediate term to operate continuously; in a simple sense, one vessel prepares to go to sea while another deploys and the third refits after its deployment. And of course, both countries must develop the training, tactics and procedures, not to mention maintenance and personnel policies, that would allow for this cycle over time. 

There are also reasons to doubt the assumption that SSBNs will be largely undetectable by adversaries in context of the Indo-Pacific. Indian and Chinese submarines, at least for the foreseeable future, are likely to be noisier than Russian, British, and French SSBNs, much less their American counterparts. Moreover, operational and doctrinal features of both navies may ease the inherent difficulties of detecting SSBNs. Both countries have a limited and well-known number of bases capable of housing them. Absent a larger number of hulls, both countries are likely to operate SSBNs in ways detectable to intelligence collection at the strategic and tactical levels. 

Indian and Chinese SSBN deployments are likely to spur greater efforts to develop anti-submarine warfare capabilities in many countries in the Indo-Pacific region. With a limited number of platforms, limited ability to spend time at sea, as well as command and control constraints (the importance of which has been raised in Ravi N. Ganesh's post), operational doctrine may derive from a modified version of the bastion concept used by the Soviets in the Cold War. Indian and Chinese SSBNs may remain in port until they 'surge' to pre-designated undersea bastions protected by anti-submarine warfare techniques and surface ships during crises. 

Aggressors may thus have incentives to attack adversary SSBNs in their home ports preemptively, as well as to find and neutralize undersea bastions. Unless China or India invests in large scale hardening — think U-boat pens in World War Two adapted to withstand nuclear and deep-penetrating conventional weapons — SSBNs will be vulnerable in their home ports, when transiting to and from those ports and likely, their bastions. 

Protecting bastions will be costly: China and India will have to improve their own anti-submarine warfare capabilities as well as devote a large percentage of their existing undersea and surface fleets to defensive measures. There are also opportunity costs; those parts of the fleet devoted to protecting SSBNs will not be available for offensive operations during crises. 

Further, if a nuclear state wants to protect against a disarming first strike, there are other potentially less costly ways of doing so. Existing or newly developed missile delivery systems (leaving aside air-launched weapons here) can be either mobile or hardened. Mobility and hardening at the very least introduce uncertainty into an adversary's calculations at, debatably, less cost and while leaving expensive and flexible naval assets available for other missions. 

Which brings me back to my original point about naval arms control. 

For those interested in strategic stability, not to mention peace, arms control remains attractive. In practical terms, there are remote prospects in the Indo-Pacific of achieving broad based disarmament for the three potential possessors of operational SSBNs, or in the case of Pakistan, diesel electric submarines armed with nuclear tipped cruise missiles.  Yet even during the Cold War, the US and the Soviet Union found ways to limit the riskiest forms of military competition. India, China, and Pakistan each possess sophisticated strategic communities well aware of the dangers of nuclear proliferation.

Thinking carefully about arms control measures for SSBNs — one of the most expensive and riskiest forms of proliferation — could begin the path toward to reducing military tensions across the entire region. Third party states like Australia and Japan affected by the nuclear rivalries at sea might provide good offices and perhaps even incentives to initiate arms control negotiations.

 Photo courtesy of Flickr user Official U.S. Navy Page.

Most discussions about the security of Asia in the 21st century beg the comparison with the East-West confrontation of the 20th. In the nuclear realm, as in other domains, the question 'Is Asia different?' is central. Judgments on the stabilising or destabilising nature of Asian nuclear weapons at sea depend on a few key parameters, on which there does not seem to be major disagreement among contributors to the debate launched in this series:

• It is generally agreed that secure second-strike capabilities at sea were a stabilising factor in the strategic relationship between great powers during the Cold war; there is no a priori reason why things would be radically different for Asia tomorrow.
• Asian nuclear powers already have a modicum of secure second-strike capabilities. Through protection, mobility, concealment and deception, at least some of their land-based missiles are de facto immune to an adversary’s first strike. Or, to put it differently: no Asian nuclear-armed country could reasonably consider that it has a disarming first strike option on another.
• Submarines armed with strategic (ballistic but perhaps also cruise) missiles would thus probably increase strategic stability in the region without necessarily being a complete game-changer.
• However, for that increase in stability to happen, two conditions would have to be met:
• All three major Asian nuclear powers would need to have them; in the meantime, access to strategic submarines by one or two (but not three) could be more destabilising than stabilising.
• Maritime nuclear forces would need to be protected from attack either through continuous at sea deterrence (CASD) or through heavy natural protection (such as the Hainan island base); otherwise, they could become tempting targets, with the risk of adding more instability than stability. This also implies an investment in nuclear force protection (anti-submarine warfare frigates, maritime patrol aircraft etc) to ensure that a ship leaving for patrol does not become an easy target; any investment in a sea-based nuclear capability implies an additional investment in non-nuclear forces.

[fold]

• These two conditions are unlikely to be fulfilled anytime soon, and the peculiarities of the Asian maritime theatre (access to oceans, nature of the waters) will make them harder to achieve than in the East-West context. This is another reason why, for operational patrols, 'bastion' practices will be more tempting than 'dilution' ones.
• Because of command and control challenges, countries which combine assertive nuclear control cultures and de-mating practices (China and India) will not naturally be inclined to allow for operational patrols of submarines. In other words, CASD will not come easily to Asia.
• That said, access to modern submarine-based secure second-strike capabilities might be faster, relatively speaking, than it was in the East-West context, due to technological developments that will make some key capabilities (accoustic discretion, secure communications, etc) easier to achieve than was the case in the 20st century.
• It is hard to argue that theatre nuclear weapons at sea (for use against other maritime forces) would increase strategic stability in the region. They may lower the nuclear threshold in a conflict.
• Finally, an inescapable feature of the Asian nuclear landscape is its multilateral nature (four nuclear countries in the region plus Russia and the US). Three independent Asian nuclear actors plan to put part of their nuclear weapons at sea, and since the beginning of this discussion, it has been learned that the fourth (North Korea) may also have plans in this regard. This 'built-in complexity' of the Asian nuclear scene may be more important, at the end of the day, than the structure of the respective arsenals of the countries concerned.

 The Lowy Institute gratefully acknowledges support from the John D and Catherine T MacArthur Foundation for this Interpreter debate, which is part of a broader research, dialogue and outreach project on strategic stability in Indo-Pacific Asia.

As several participants in our debate have argued, nuclear ballistic missile submarines (SSBN) can have a positive effect on strategic stability in Asia and globally. But they do not exist in a vacuum. New military capabilities, and strategies that take advantage of them, are being developed and deployed in the Indo-Pacific that make the gradual proliferation of sea-based nuclear weapons dangerous rather than stabilising. 

These novel weapons, such as cyber and electronic warfare, anti-satellite missiles and hypersonic technology, add new dimensions to both conventional warfare and nuclear deterrence. Their development, along with their roles in comprehensive strategies, such as the US’s Air-Sea Battle concept, requires us to ask whether the introduction of Chinese and Indian sea-launched nuclear weapons will only create instability and the risk of escalation in conflict. 

The role of SSBNs is to provide an assured second-strike capability to a nation's nuclear deterrence. Essentially, a second strike capability acts as a kind of fail-safe by ensuring that any aggressor takes on the risk of being attacked by nuclear weapons in-kind. Thus, theoretically, SSBNs and assured second strike should lead to a more stable strategic system in the Indo-Pacific by deterring any potential disabling first strike. [fold]

As Rod Lyon has argued, the SSBN can make an aggressor think twice, as long as the threat of the platform is credible. It is mobile, quiet and difficult to track. Once professional crews, reliable communication technology and effective command and control are established, the SSBN can act as a credible deterrent. But if the SSBN is to play a positive role in strategic stability, communication with state leadership must be guaranteed. 

Communications with submerged submarines, both conventional and nuclear, are established through very low frequency and extremely low frequency programs. These involve large antenna installations that are part of a state's military communications network. Thus for example India, conducting sea-trials of its first SSBN, has started construction of its own very low frequency station. 

But what happens to deterrence and stability if such communications come under attack?

In the Cold War, the main way to neutralize an adversary's submarine-launched nuclear weapons was through anti-submarine warfare; detecting and tracking enemy SSBNs and, in the event of war, destroying them before they launched. 

There was, of course, the risk that during a conflict anti-submarine warfare could induce 'use it or lose it' decisions on a state's leadership. That destabilising factor is now amplified by another possibility raised by new technologies: the prospect that a state's communications with its nuclear deterrent force could be cut in times of crisis.

What would happen in a future conflict in which the opening attack involved the use of cyber and other capabilities to disrupt or destroy military communication systems? How could we be certain that SSBN commanders, cut off from political authority, would not launch their weapons? 

This goes to wider questions about vulnerability of communications, including satellites, in conflict. The head of US Air Force Space Command recently said that if one of the Advanced Extremely High Frequency satellites, a backbone of US military communication, was taken out 'we could potentially have a situation where the president can't communicate with forces in that part of the world.'

There is no guarantee that striking another power blind or dumb in the midst of crisis would add to stability. Thus the US Air-Sea Battle concept has an uneasy relationship with nuclear deterrence. Designed to counter Chinese anti-access and area-denial capabilities, Air-Sea Battle requires the integration of all 'interdependent warfighting domains (air, maritime, land, space and cyberspace)' in order to 'disrupt, destroy and defeat' enemy forces. The strategy calls for the disruption of enemy 'command, control, communication, computers, intelligence, surveillance and reconnaissance' systems before attacking their weapon systems and capabilities.

Many of these communication systems, like the low frequency installation India is building, are dual-use in the sense that they could network with conventional and nuclear forces. Thus it is possible to foresee a situation where a 'blinding' campaign like that envisioned in Air-Sea Battle could involve attacks on an installation that also communicates with SSBNs, radically disrupting a state's control over its sea-based nuclear arsenal. Presumably, India would face a similar problem if Pakistan or China ever planned to target its communications at the outset of a conflict.

These are some of the complexities and scenarios that will need to be thought through if the introduction of Chinese and Indian nuclear-armed submarines is to reduce risks of conflict rather than heighten them.

The Lowy Institute gratefully acknowledges support from the John D and Catherine T MacArthur Foundation for this Interpreter debate, which is part of a broader research, dialogue and outreach project on strategic stability in Indo-Pacific Asia.

Photo courtesy of Flickr user U.S. Navy Official Page. 

How will the deployment of ballistic missile submarines by China and India affect the Indo-Pacific strategic landscape? What effect will these deployments have on stability in the region? 

Unsurprisingly, the contributions thus far have shown that the picture is, as Rory Medcalf put it, 'murky.' As Bruno Tertrais pointed out, much of the inmpact on stability from these deployments will depend on the quality of the submarines, the range and reliability of their accompanying missiles, and the skill of their crews, as well as on the anti-submarine warfare efforts of their prospective foes. At the same time, as Tom Mahnken noted, a greater sense of second-strike assurance may embolden rather than relax at least China's ambitions. Meanwhile, Rod Lyon has observed that, even with all the qualifiers, strategic submarines tend to make adversary decision-makers think twice about attempting a first strike.

Thus far, the debate seems to be clustering around a general view that the deployment of ballistic missile submarines (SSBNs) is neither a panacea nor a catastrophe for stability, and that much will turn on how they are operated and on how much they are relied on for strategic advantage. 

One aspect of their deployment that has not been sufficiently remarked upon, however, is how the deployment of systems as strategically significant as ballistic missile submarines may influence regional naval doctrine and operating patterns, and even national strategic objectives more broadly. Lyon touched on this point when he wrote that 'even vulnerable SSBNs might have value if deployed in protected bastions, behind layered defensive screens, exploiting known seabed topographies, confusing the targeteer with diversionary noisemakers, and keeping the warhead loadings low per boat.'

The broader point is that effective deployment of a ballistic missile force is not simply about getting a boat into the water with operational missiles loaded. [fold]

Rather, attaining more than a bare bones second-strike capability at sea means ensuring those submarines are survivable, can communicate reliably with national leadership, and that their missiles can reach their assigned targets. This is by no means an easy task for a country like China when one faces a highly capable potential adversary like the US Navy, not to mention the Japanese Maritime Self Defense Force, the Royal Australian Navy, and others. 

Accordingly, if China is really serious about achieving an assured second strike capability with its ballistic missiles submarines – by no means an unreasonable supposition, given the cost and scale of the effort – it will need to ensure that these submarines can meet the criteria laid out above. This might be done, as Lyon indicated, by developing sufficiently quiet submarines. We can presume the PLA Navy is working at that assiduously. But will they be sufficiently confident that their submarines are quiet enough to survive, and to survive for long enough? If not, the Chinese may look to other means of protecting their submarines, means that could have considerable strategic consequences. 

Let's look backwards to give some context. As Owen Cote has related, in the 1960s and early 1970s, the Soviet Union deployed its early cruise missile and ballistic missile submarines forward, into the Atlantic. Starting in the mid-1970s, however, the Soviets, alerted to the vulnerability of their submarines by the Walker spy ring, began shifting to a 'bastion' strategy in waters nearer to the USSR, protecting the valuable missile submarines from the US Navy's anti-submarine warfare (ASW) capabilities with layers of defences including air cover, surface ships, and so forth. This entailed a major shift in the doctrine and operating patterns of the Soviet Navy that changed the 'waterprint' of its naval forces. Protecting their boomers, in other words, drove major changes in how the Soviets operated their naval forces, in this case back from forward positions to zones closer to the homeland. 

If China were also concerned about the vulnerability of its missile submarines to the ASW capabilities of the US and its allies, it too might seek 'bastions' and/or other means of protecting these submarines. These efforts at protection could include establishing a higher military presence and even attaining greater control over airspace above the seas in which the PLA Navy would want to operate its submarines. This in turn would mean that Chinese forces might operate and train in seas and airspace that had not traditionally seen much PLA presence and at considerably higher tempos and in a more sophisticated fashion than in the past. China might even seek to obtain formal or informal control or operational dominance over certain seas and airspace – either through gentle means or through coercion – to ensure the security of its missile submarines. 

Such efforts would, of course, have significant political ramifications. But it would hardly be the first time military requirements had helped form political objectives. US requirements for bases during the Cold War drove much of Washington's alliance policy, particularly outside of Europe. And a good bit of Britain's policy in its imperial heyday was motivated by the need for coaling and refitting stations. 

This point should not be carried too far. China is sensitive to political constraints on the exercise of its military power, and we can assume that part of the appeal of SSBNs for Beijing is that they hold out the promise of being able to operate independently and without much fuss. 

Still, in thinking about the implications of China's ballistic missile submarines on stability, we should not ignore that the demands of survivability and operational effectiveness could also entail considerably broader military operational and ultimately political consequences. Much will depend on how much China values these submarines, how quiet it believes them to be, the effectiveness of US and allied ASW efforts, the intensity of rivalry in East Asia, and a range of other factors.

But the point is that the effort to deploy a genuinely survivable and effective ballistic missile submarine force could have consequences well beyond the narrow concerns of submarine quality, crew skill, and missile range.

The Lowy Institute gratefully acknowledges support from the John D and Catherine T MacArthur Foundation for this Interpreter debate, which is part of a broader research, dialogue and outreach project on strategic stability in Indo-Pacific Asia.

Photo by Flickr user UK Ministry of Defence.

Both the draft nuclear doctrine released in 1999 and the official nuclear doctrine released later in 2003 state India's commitment to a minimalist nuclear posture.

This nuclear minimalism was best advocated in the policy of credible minimum deterrence (CMD). Two assumptions inform the concept of CMD. First, that deterrence can be projected at low numbers, and second, that a ready arsenal – delivery vehicles mated with warheads at continuous alert – is unnecessary. The commitment to low numbers of warheads meant that CMD could help avoid unnecessary 'vertical proliferation'. Such a posture was therefore considered propitious for nuclear stability.

But will CMD remain valid as India shifts its nuclear arsenal to the sea? The coming of the Arihant, India's first nuclear-powered and nuclear-armed ballistic missile submarine (SSBN), constitutes a formidable challenge to India's posture of credible minimum deterrence and therefore, also to strategic stability in the region.

The present configuration of INS Arihant allows it to carry 16 nuclear-tipped missiles. By the end of this decade, India plans to deploy five to six such SSBNs. Clearly, the warheads required to arm these submarines would alone be close to the current estimates of the total number of nuclear weapons (between 90-110) in India's arsenal. This increase in numbers would not be alarming if India was to shift its entire nuclear arsenal underwater as France and Britain have done. In fact, in 2000, in a well argued and equally well received book on India's nuclear strategy, Raja Menon – an influential strategic analyst and a retired rear admiral – suggested precisely this course.

Various factors militate against such a prospect, however. [fold]

For one thing, the current generation of India's sea-launched ballistic missiles lack the range for an underwater deterrent to be credible. The K-15 or Sagarika, the only missile ready to be deployed on Arihant, has an effective range of only 700km. Though this may be sufficient for projecting second-strike capability against Pakistan, it is clearly inadequate for retaliating against China. With such a short range, Indian SSBNs would have to enter dangerous waters in East Asia to release their payloads. India, therefore, will continue to rely on aircraft and missiles for nuclear delivery. The rivalry among India's army, navy and air force will also frustrate any shift to an underwater-only nuclear arsenal. All three services want a part of the nuclear arsenal, both for budgets and prestige. This is similar to the US experience during the initial years of the Cold War.

Furthermore, the number of Indian nuclear warheads would spike if the Defence Research and Development Organisation's (DRDO) ambitious plan of introducing multiple independent re-entry vehicles (MIRV) into India's nuclear delivery systems bear fruit. The DRDO claims that, in the near future, Indian missiles could be capable of carrying 4 to 12 nuclear warheads atop a single missile. Multiple warheads clearly imply a multiplying arsenal. 

Then there is the question of India's nuclear readiness. The conventional wisdom is that India's nuclear weapons are in a state of 'recessed deterrence' – disassembled, de-mated and de-alerted. In case of a nuclear emergency, operationalising the nuclear arsenal would require coordination among multiple agencies such as the DRDO, the Atomic Energy Commission (AEC) and the armed forces. All these agencies control different subsystem of the nuclear arsenal: AEC controls the nuclear core; DRDO controls the non-fissile triggers and the armed forces control the delivery vehicles. Such diffusion automatically suggests a disassembled arsenal.

However, as Vipin Narang has argued recently, the idea that 'India keeps its nuclear weapons is a disassembled state...is largely now just a myth'. DRDO has publicly articulated its position of 'canisterising' or 'encapsulating' all nuclear delivery systems, which requires that a 'warhead is likely to be pre-mated to the delivery vehicle and kept hermetically sealed for storage and transport'. The rationale emanates from the need for a credible second strike capability. As the DRDO chief explains, 'In the second strike capability, the most important thing is how fast we can react.  We are working on cannisterised systems that can launch from anywhere at anytime'.

Though last-minute checks and balances would still be in place, this is not a picture of a 'disassembled' nuclear force. This is particularly true of nuclear-armed submarines. Since such submarines may have no links with the mainland during a patrol, warheads cannot be possibly detached from the delivery vehicles. In the case of land-based and air-based delivery platforms, coordination among multiple agencies is still possible, but an underwater deterrent requires a ready arsenal. 

So Arihant and its progenies will not only increase the size of India's nuclear arsenal but also its readiness, making the idea of a CMD practically meaningless. This could have a spiral effect on Pakistan, which would increase its own weapons production and battle readiness. We are already witnessing this, with increasing numbers in her nuclear arsenal and intentions to develop tactical nuclear weapons. It may also lead to new proliferation challenges for India if Pakistan avails of China's services to acquire its own nuclear triad.

The Lowy Institute gratefully acknowledges support from the John D and Catherine T MacArthur Foundation for this Interpreter debate, which is part of a broader research, dialogue and outreach project on strategic stability in Indo-Pacific Asia.

Image courtesy of Wikipedia.

The danger of sea-based nuclear weapons in Asia depends on the strategic context of the potential protagonists, along with the particulars of the platforms, delivery system, and doctrines.

Perhaps the least menacing in the short term is the interaction between India and China as each builds its sea-based nuclear capability. There are still years to go before each state has systems coupled with the need to deploy them in locations that could lead to dangerous interactions.

A second dyad, between US sea-based nuclear weapons and the growing Chinese maritime nuclear arsenal, has the potential for misunderstanding, risk-taking, and escalation, but Washington and Beijing are not in a state of on-again, off-again militarised hostilities. This, coupled with the distance from China that US nuclear-armed ballistic missile submarines are likely patrol, limits some potentially dangerous interactions.

The India-Pakistan dyad, however, carries the potential to be the most menacing in the short-to-medium term.

Both India and Pakistan are at the initial stages of deploying nuclear weapons on submarines. Being new to a deployed technology and operational technique does not mean the two governments and their militaries will not be careful or capable. Both states are likely to be highly cautious and professional in their deployment of these capabilities. However, there is always a learning curve with new capabilities and therefore always chances for misperception, miscalculation, and the threat of escalation.

Three additional factors in the South Asian context make this newly emerging set of capabilities particularly troubling. [fold]

The first is the very short range of India's first generation submarine-launched ballistic missile (the K-15 has a reported range of 750km) and Pakistan's likely submarine-launched cruise missile (the Babur, with a reported range of 700km). The second is that it appears Pakistan will be deploying its sea-based nuclear capability in a dual-use platform, a diesel-powered attack submarine. Finally, the two states have a history of wars and militarised crises over a range of disputes that will not be resolved anytime soon. 

Unlike the deployment of nuclear warheads on land-based missiles or nuclear gravity bombs, sea-basing of nuclear weapons carries a much greater chance of close-up and regular interaction between the forces of two potential protagonists. In peacetime, once India and Pakistan actually have operational platforms deployed, it can be expected that each side will seek to gather intelligence on the acoustic signature of the other side's submarines, along with information about operating patterns and locations. This creates chances for accidents, incidents, or heightened tensions, particularly as the relatively short ranges of the missiles mean that deployment areas may be relatively close to the other's territorial waters.

Yes, such submarine-versus-submarine interactions occur already without any public acknowledgment of increased tensions, but the importance of nuclear weapons may cause both sides to take greater risks both to gather intelligence and to defend a nuclear-armed platform. Similarly, both sides may become more aggressive in patrolling and defending territorial waters, contiguous zones, and even exclusive economic zones if they want to deny the other side from gaining operational familiarity with a particular stretch of water.

If another militarised crisis between India and Pakistan were to occur after the deployment of sea-based nuclear weapons, the chances of inadvertent escalation will be higher than in an environment absent these platforms. In the case of Pakistan's likely nuclear platform – an Agosta-class submarine basically indistinguishable from its conventionally-armed counterpart – Indian naval commanders and their civilian leadership may be faced with a difficult dilemma. Protecting India's surface and submarine fleet from Pakistan's submarines in a crisis or war requires aggressive detection measures and attacking potential contacts. However, India may feel constrained if it does not want to inadvertently escalate a crisis or conflict by destroying the 'secure second-strike' portion of Pakistan's nuclear triad. If India were to destroy a Pakistani submarine carrying nuclear-armed missiles as part of a conventional war, would Pakistan's leadership interpret this action as crossing a nuclear threshold?

Similarly, in a future crisis or conventional war, what would Pakistan do to place itself in a better position to track and, if possible, destroy the INS Arihant or its successors? Pakistan has shown itself both willing and able, as far back as 1971, to undertake long-range, risky submarine operations in an attempt to strike at high-value Indian assets on India's east coast. Would India view such a Pakistani operation in a future crisis as escalatory? What would its response be?

The Lowy Institute gratefully acknowledges support from the John D and Catherine T MacArthur Foundation for this Interpreter debate, which is part of a broader research, dialogue and outreach project on strategic stability in Indo-Pacific Asia. 

In his introduction to this Interpreter debate, Rory Medcalf raises the important question of how nuclear-armed ballistic-missile submarine (SSBN) programs in Asia influence strategic stability.

Making such an assessment for any one weapons system in isolation is fraught with difficulty, as judgments are inevitably based on assumptions about doctrine, employment, escalation, and strategic concepts. Technical details also matter a lot, as was demonstrated in the late Cold War by the development of the highly precise Trident D5 (which gave the US SSBN fleet the ability to conduct counterforce missions against hardened targets) on the one hand, and the appearance of very quiet Soviet submarines (pictured) on the other. Strategic stability is thus always a question of net assessment.

Viewed in this light, the scale and scope of the programs under development in Asia today seem unlikely to change fundamental power relationships and military balances. India and China have toyed with SSBN technology for decades, and it is difficult to see either action-reaction patterns, or an out-of-character acceleration, that would indicate an incipient SSBN arms race. That said, the fact that SSBNs are now being introduced into the regional mix of capabilities throws a useful spotlight on the influence of geography, and on Chinese views about the vulnerability of their nuclear forces. Both of these factors are of fundamental importance to net-assessment-based judgments of strategic stability in the Western Pacific, and highlight the strengths of the current strategic order that China must still overcome.

The attraction of SSBNs is that they can be difficult to find and destroy, particularly if they are either isolated from adversary ASW forces in a 'bastion' or able to hide in the vast expanses of deep water found in the Pacific, Atlantic, and under the Arctic ice cap. Strategic geography thus favoured the employment of SSBNs by the main nuclear powers of the Cold War (the US, Soviet Union, France and Britain), whose submarine bases had direct access to suitable deployment areas.

Not so in China's case. While the waters of the northern South China Sea are deep, they are also confined. [fold]

The need to pass through chokepoints into the Pacific places Chinese submarines at a disadvantage, as it makes it easier to for US and allied ASW forces to detect and track Chinese SSBN patrols passing into the Pacific, or to block them through mining in wartime. Moreover, the South China Sea is ringed by US allies, and any 'bastion' the PLA Navy might attempt to establish could be contested by a range of US and allied systems operating from friendly territory. Those systems would of course themselves be at risk of Chinese attack, but the heart of a conventional battle would not be a good place for an SSBN to be.

'Deploying' the SSBN in the cave complex on Hainan Island might align more closely with the Chinese preference to keep close control of nuclear warheads, but it would significantly limit the strategic benefit of having an SSBN capability: if they remain inside the caves too long, the Chinese SSBN force risks being disabled by a US strike (even if this required nuclear weapons). Should they leave the caves in a crisis, however, China risks sending inadvertent escalatory signals, and the boats would enter waters likely to be teeming with US attack submarines.

All of this raises the question of why China is developing SSBNs in the first place. The reasons are far from clear, and a coherent strategic rationale may not even exist in Chinese minds. SSBN development is consistent with the long-term features of Chinese nuclear strategy and force modernisation, which emphasise survivability through dispersion of its land-based systems. With the DF-31 and DF-31A, China can now retire its only silo-based system, the large DF-5 ICBM, and rely completely on solid-fuel, road mobile nuclear missiles.

And yet the development of an SSBN force indicates that China is not fully confident in the survivability of its land-based nuclear forces, and is at least hedging its bets. This is not fully unjustified, as land-based missiles still have to operate in prepared deployment areas that are vulnerable to the large-scale nuclear suppression campaign, of which the US is still capable. US attempts to build a survivable launcher for its own land-mobile Midgetman missiles during the Cold War are a salutary reminder of the inherent fragility of mobile ICBMs to nuclear blast pressure. Adding SSBNs to the mix would certainly complicate US planning for the unlikely event that it should ever consider a disarming strike on China, but it does not change the basic source of China's vulnerability, which lies in the numerical imbalance of the nuclear forces of both countries.

Investment in SSBNs thus indicates that China remains uncomfortable with the limits imposed by its small nuclear arsenal. But the scale of China's investment doesn't really address the issue. SSBNs put a lot of eggs into one basket and are no panacea for the problem of survivability, especially given China's geographic disadvantage. As such, their appearance in the region is a useful reminder that the broader factors underpinning strategic stability in the region — US military capabilities, including its nuclear arsenal, and the alliances they support in the Asian littoral — have a lot going for them still.

The Lowy Institute gratefully acknowledges support from the John D and Catherine T MacArthur Foundation for this Interpreter debate, which is part of a broader research, dialogue and outreach project on strategic stability in Indo-Pacific Asia.