Having read the initial round of contributions to this debate, I must say I'm not a believer in the idea that sea-based nuclear weapons are destabilising. In large part, that's because I'm finding it difficult to construct a scenario in which a senior defence adviser ever uses the sentence, 'Mr President, we have to attack now, they have sea-based nuclear weapons.' True, the future is an unwritten page so it's impossible to say with certainty that such a sentence will never be uttered. But on any rational calculation of probabilities, I know which way I would bet.

Does that mean we can look with equanimity at the forthcoming deployment of nuclear weapons at sea by Asian nuclear powers? Well, not entirely. It's true that some force structures are more destabilising than others. In particular, deployment of vulnerable high-value targets doesn't contribute to good crisis stability. So if Asian powers were to deploy large warhead numbers in vulnerable, noisy SSBNs, they'd have to anticipate losing at least some of those boats early in a conflict. Still, 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. Quiet SSBNs would have value without that supporting architecture.

Deployment of nuclear weapons at sea doesn't guarantee invulnerability. But the development should typically be seen as positive in relation to Asia's current monopedal force structures. No Asian power has a strong 'air-breathing' strategic leg. They're mainly just land-based forces. Having a sea-based leg is something of a safeguard against technological surprise.

Moreover, I think there are important political gains to be derived from sea-based systems, and those might be more important than the strategic and technological ones. First, such systems suggest a commitment to a durable, resilient nuclear force. They suggest that resort to nuclear weapons needn't be — and won't be — a rushed decision. Second, they devalue the benefits to an adversary of a bolt-from-the-blue attack upon the land-based component of the force, usually sited in relatively static target sets. Third, because they make such an attack upon the land-based systems less likely, they help reassure the population of the nuclear weapon state that they aren't mere nuclear cannon fodder, and thus help sustain political support for the arsenal.

Finally, I'd make one simple observation: if Asia's nuclear-armed countries want to build and deploy sea-based nuclear weapons, who's going to stop them? Nations typically have the right to get their own defence procurement decisions wrong. And in this case it's far from evident that decisions to deploy nuclear weapons at sea would be wrong.

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 Wikipedia.