The world's strategic, political and nuclear landscape is changing, and the United States and its allies must adapt: that is the chief point of agreement among all of the contributors to our blog debate on extended nuclear deterrence (END).
But the fundamental question is how? Here the experts in our global debate part company.
Should the priority be on reinforcing the credibility of END guarantees through alliance consultations, or perhaps changes to arsenals, deployments and declaratory policy? Should the focus be on enhancing non-nuclear extended deterrence, such as conventional strike and missile defences?
Should allies contribute more to their own security? Or could diplomacy play a larger role in easing the mistrust that feeds the need for deterrence?
These are among the questions that have recurred throughout our debate. I will offer my own interpretation of key points from the discussion, before concluding with some thoughts on where this leaves policymakers.
George Perkovich rightly identifies that nuclear weapons are useful only against existential threats, and suggests that one reason the Obama Administration's pursuit of nuclear disarmament makes sense is because the conventional military balance favours America. I am not so sure, at least in those parts of Asia most affected by rising Chinese power.
The uncertainty that this power shift provokes among Washington's Asian allies, largely explains why they are hewing closer to END at the very time when the US is reducing its reliance on nuclear weapons.
This point informs the arguments of Tom Mahnken and Duncan Brown, who call for a dialogue about adapting END, not downgrading it.
Still, Tokyo, Seoul and Canberra might take comfort in Perkovich's reminder that US policy is for some form of END to be around for as long as nuclear arsenals exist.
Bruno Tertrais notes the non-proliferation benefits of END and argues that it is alive and changing. But he also acknowledges that a greater reliance on non-nuclear forces need not make extended deterrence less credible. Having a range of non-nuclear capabilities might prevent the wielder of the nuclear umbrella being self-deterred by a brutal choice between all-out nuclear war or backing down.
Interestingly, despite his general advocacy of END, Tertrais recognises it as relying more on the psychology of leaders than the proximity of weapons — an argument against those, for instance in Europe or South Korea, who support tactical nuclear deployments.
Shen Dingli argues that recent trends and events suggest that END is moving towards irrelevance. He suggests that events in Northern Asia in 2010, the sinking of the Cheonan and the shelling of Yeonpyeong island, amount to a failure of END. Yet, as others such as Nobu Akiyama argue, this could simply be the stability-instability paradox in action.
In a sense, these events might even show END as working: after all, both Seoul and Washington tempered their responses with a clear sense of proportionality. And, as some other contributors note, the various consultative dialogues on END involving Washington, Seoul and Tokyo could be a sign of its stable adaptation.
The vital ingredient of proportionality informs the views of many other contributors, notably Hugh White and Fiona Cunningham. But they reach rather different conclusions. White asks whether the United States really would use nuclear weapons to defend an ally in circumstances where a nuclear adversary could strike American territory, and moreover where critical American interests were not at stake.
This leads him to conclude that in most circumstances END is becoming an anachronism. He does not say much about what might take its place, although his second post suggests reasons why an ally like Japan might come to want nuclear weapons of its own. This point is alluded to by Raoul Heinrichs, who also offers a view on the Australian context.
Stephan Fruehling, Benjamin Schreer and, in his second post Tertrais, remind us that the psychology of the prospective adversary is at least as important as that of the nation wielding the nuclear umbrella, or indeed of its threatened ally. For this reason, they argue, END remains likely to reduce the risk of war.
One issue that was not explored at depth in the debate, yet which cannot be overlooked, is whether the potentially catastrophic consequences of nuclear escalation are worth that reduced likelihood of conflict.
Jeffrey Lewis grabs our attention by proclaiming there is no such thing as the nuclear umbrella; even as a metaphor, it would seem, this term can be misleading. There are alliances, he says, and there are nuclear weapons, but the link between them is an inference, albeit reasonable. From here, he argues that the credibility of END should be linked, not to numbers or forward deployed capabilities, but to the strength of alliences — consultation and joint planning, as well as their shared interests and values.
Such ideas may remain difficult to sell in some parts of Seoul and Tokyo. Hyun-Wook Kim argues that END remains important and generally effective, and refers to the prominent calls in South Korea for the return of US tactical nuclear weapons to the peninsula. However, he also asserts that the Cheonan and Yeonpyeong attacks by North Korea prove that US extended deterrence has failed.
These events feature widely in our debate, but their meaning remains contested. Kim sees them as a reason for more deterrence; Shen as reason for less.
Japanese experts Nobu Akiyama and Hirofumi Tosaki both point broadly to the continued relevance of END, but also to its limits. They focus on how the Asian threat environment is changing, and how the US and its allies thus need to strengthen their non-nuclear deterrent capabilities.
They also suggests a need to look for a new basis of strategic stability, notably between the US and China, with a role for diplomacy and confidence-building measures in reducing mutual threat perceptions. Richard Bush takes this point further, emphasizing the need to persuade Beijing that restraining North Korea's nuclear weapons ambitions and belligerent behaviour is in China's interests. Such a move would reduce the need for the US, South Korea and Japan to strengthen their capabilities and alliances.
One striking thread throughout the discussion, is how much psychology and perception will matter in determining whether the nuclear umbrella or, if one prefers, an inclusive form of core deterrence, can weather the strategic turbulence that may well lie ahead. In the end as Fiona Cunningham and several other contributors imply, it could be an act of choice — an open affirmation of belief in END — that helps reduce the likelihood that it will ever need to be tested.
Extended nuclear deterrence is not dead. But, to paraphrase a great Italian novelist, for its positive effects to stay the same, it will have to change. As global efforts to reduce nuclear dangers continue, END will inevitably be examined as a source both of stability and possibly less desirable effects.
Moreover, nations that consider themselves protected by US nuclear guarantees, have to address questions about their own credibility as advocates of nuclear non-proliferation and disarmament. In a world of diverse and changing threats, their continued embrace of END is understandable. But they would do well to consider how END might most safely be refined for 21st century circumstances.
For a start, this might involve allies agreeing that a practical and moral nuclear umbrella can function only against existential threats, along with their renewed willingness to contribute more towards non-nuclear defence.
The Nuclear Reactions column is supported by the Nuclear Security Project of the Nuclear Threat Initiative, as part of a wider partnership between the NSP and the Lowy Institute.
Photo by Flickr user jordi.martorell.
