Debating Extended Deterrence

The Interpreter, the blog for the Lowy Institute for International Policy, has a fascinating debate posted on the role and sustainability of extended nuclear deterrence in the 21^st century.  The participants include George Perkovich of the Carnegie Endowment for International Peace, Bruno Tertrais of the Fondation pour la recherché strategique, Shen Dingli of Fudan University in Shanghai, and Hugh White of the Lowy Institute.  The debate addresses several questions:  Is the age of extended nuclear deterrence over?  Is the U.S. “nuclear umbrella” still viable? And do alternatives to this policy exist?

The debate coordinators have already started posting responses from the participants, readers, and other experts in the field so taking a look at the debate in full would be well worth the effort.  In the mean time, here is a brief overview of the initial arguments, as well as my thoughts on the subject.

George Perkovich is up first and believes extended deterrence may be waning in its ability to deter limited threats:  “What [nuclear weapons] have been able to deter, generally, is large-scale aggression that would threaten their own existence or those of their protectorates.  In other words, nuclear weapons deter only those threats against which it is credible to use nuclear weapons.”  This has certainly been true regarding recent incidents on the Korean Peninsula—the most recent being the North’s sinking of a South Korean corvette, the Chenoan, in March and its shelling of Yeongpyong Island in November.  Deterrence and, by extension (literally), extended deterrence rely on the credible threat that nuclear weapons will be used in response to aggression.  The U.S. has shown over the years that it is unwilling to use nuclear weapons in response to conventional or relatively minor provocations.

Bruno Tertrais, on the other hand, is bullish on nuclear deterrence having a long shelf life:

The credibility of the U.S. ‘nuclear umbrella’ was the focus of considerable debate during the Cold War, and there is no reason why this debate will not continue…Not only has [extended deterrence] survived the end of the Cold War, but its scope has even expanded.  In Europe, NATO has almost doubled in membership in the past 20 years, and the new members are keen to emphasize how much the U.S. umbrella matters to them.

Tertrais initial point is quite correct, debate over the credibility of extended deterrence has been going on since its early days and will likely continue for the foreseeable future.  His point that the “nuclear umbrella” being extended to more and more countries since the end of the Cold War as evidence of its sustainability is less convincing.  Adding more NATO members hardly makes deterrence more credible because it increases the variables involved.  Will the U.S. be as willing to respond to Russian aggression against Lithuania or Estonia, as it would be to respond to an Iranian attack on Israel or a North Korean nuclear attack on Seoul?  New protectorates require new calculations of what threats can be deterred and what kinds of aggression will be responded to.

Tertrais also notes the new commitments made by the Obama administration’s 2010 Nuclear Posture Review that it would only respond to nuclear attacks with nuclear weapons and would eschew use against countries that have maintained their commitment to the Non-Proliferation Treaty.  This commitment essentially codified the practice mentioned by Perkovich, but Tertrais believes the deployment of regional missile defense architectures—and unwillingness to declare a No First Use policy—will supplement extended deterrence against limited threats.

Shen Dingli echoes Perkovich’s concerns and notes the effect this has already had on ally decision-making pursuing an independent nuclear deterrent—specifically citing Israel’s clandestine nuclear arsenal.  Shen seems to see deterrence as a game played amongst great powers and that America’s unwillingness to respond to limited threats will see extended deterrence continue to wane.  This is far from an entirely pessimistic assessment though.  Shen sees the lessening of nuclear tensions between—and the greater incentive to cooperate among—great powers will supplant extended nuclear deterrence as the 21^st century progresses.

Hugh White makes a largely overlooked point,

…[T]he costs of nuclear attack are so high that nothing except the defence of America’s own territory and independence would justify them.  In the Cold War, when it seemed one power could dominate Eurasia, America’s own security appeared to be at risk for a Eurasian hegemon.  Today, with at least two and maybe four major Eurasian powers, that risk seems very remote.

U.S. geography and the lack of a potential challenger in its own hemisphere still give it an advantage over any other great power.  Two large oceans and hundreds of nuclear weapons stand between the U.S. and any large-scale aggressor.  Despite legitimate concerns over China’s rise it’s unlikely it could dominate the Eurasian hemisphere given it’s Russian, Japanese, and Indian neighbors.

White essentially addresses the elephant in the room:  Is extended nuclear deterrence really worth it?

When debating the merits of extended nuclear deterrence it is important to determine what its goal should be.  There are two main, interrelated purposes to extended deterrence:  protecting allies from either conventional or nuclear aggression and preventing nuclear proliferation by removing the need for allies to pursue their own nuclear arsenals in the face of possible conventional or nuclear aggression.  The latter has been fairly successful—with one major exception being Israel’s unconfirmed nuclear arsenal—but the United States has gone to great lengths to prove the credibility of its offers to protect allies.   The former has a mixed record as various states under the U.S. nuclear umbrella have suffered a varying degree of attacks ranging from terrorism to the sinking of a ship at sea or shelling of a disputed Island but have largely—with some notable exceptions—been protected from full-scale aggression.

If U.S. determination not to see nuclear weapons spread, even to staunch U.S. allies, is the priority, then continuing—and perhaps extending—the so-called nuclear umbrella is appropriate, but would it really be contrary to U.S. interests if South Korea or Japan obtained nuclear weapons in the face of North Korean aggression or China’s “peaceful” rise?  Or would a Fourth Reich necessarily be the outcome of a German nuclear arsenal?  This is not to propose, as Kenneth Waltz did in his famous 1981 Adelphi Paper, that more nuclear weapons states might be better—instead, it is to say that more may not necessarily be worse than the current status quo.  If deterring conventional or nuclear threats against allies capable of defending themselves—through either conventional or nonconventional means—is the priority, then it might be time to rethink extended deterrence because American efforts to prove that its security guarantees are meaningful could put it in a position to have to prove its worth in ways that are not necessarily congruent with its own interests.

Extended nuclear deterrence will remain viable only as far as the provocation reaches a level at which the United States will be willing to respond with sufficient (i.e. nuclear) force.  The United States will still occasionally have to go to great lengths to prove the credibility of its security guarantees and with no assurance that its efforts will be successful but always with the risk of drawing U.S. forces into conflicts not necessarily in America’s interests.  Under these circumstances, perhaps phasing out the U.S. nuclear umbrella—and implicitly consenting to U.S. allies obtaining the means to defend themselves—might be a more prudent option.