I wrote my August Bulletin of the Atomic Scientists column on the fallacy of extending deterrence through tactical nuclear weapons. Here’s an excerpt:
The problem with relying on tactical nuclear weapons as tools of extended deterrence is that they are archaic arms that serve no demonstrable military purpose, and their growing financial and opportunity costs outweigh any assurance benefit. In the event of a nuclear attack against an ally, the presence of these weapons on their territory will not increase the likelihood of a US nuclear response. In so far as nuclear weapons play a role in assuring allies, US strategic nuclear forces do the heavy-lifting.
The real lifeblood of extended deterrence lies in an ally’s confidence in the strength of its political relationship with the United States. If relations fray, then extended deterrence will be perceived to be weak — no matter how many or what kinds of nuclear weapons the United States possesses. Increased security cooperation with allies in the areas of conventional force projection and regional missile defense as appropriate can be particularly strong indicators of commitment given the current threat environment. So too can stronger economic and cultural ties and close coordination with allies in pursuit of better relations with Russia and China.
As long as the United States and its allies lean on outdated nonstrategic nuclear weapons as a crutch, the easier it is to avoid difficult but much needed discussions about how Washington can continue to guarantee the security of its allies — especially as geopolitical and budgetary realities compel the country to continue to reduce its reliance on nuclear weapons.
Read the whole thing here.
Below are a few additional thoughts and some items that didn’t make it to the final draft…
In testimony before the Senate Energy and Water Appropriations Subcommittee on July 25, Keith Payne, one of the authors of the George W. Bush administration’s Nuclear Posture Review, declared that “The US has nuclear assurance commitments to 30 or more allies and the push for Minimum Deterrence undoubtedly threatens our capability to assure allies in some important cases.” Rarely are such statements followed by a detailed accounting of these anonymous allies and how US nuclear weapons contribute to their security in each case. In fact, those who trumpet the importance of the extended deterrence function of US nuclear forces often put forth wildly divergent estimates of the number of countries covered by the US nuclear umbrella.
For example, in October 2008, then-Secretary of Defense Robert Gates proclaimed that “over two dozen allies and partners…rely on our nuclear umbrella for their security, making it unnecessary for them to develop their own.” An August 2009 Defense News Editorial claimed the US “nuclear protective umbrella covers some 40 nations.” In October 2009, budget analyst Andrew Krepinevich wrote that “the United States must be prepared to defend both itself and over a dozen other countries from nuclear attack.”
Pointing this out is not to suggest that nuclear weapons do not play some role in the reassurance of US allies. Rather, it is to suggest that more rigorous analysis is needed before throwing around blanket assertions that US nuclear weapons assure X number of allies or that Y state might acquire its own nuclear weapons if the United States makes changes to its nuclear posture (such as doing away with tactical nuclear weapons). For example, as Josh Pollack has written, “If Turkey should ever decide to build a Bomb, how Ankara’s leaders judge the status of Iran’s nuclear program and whether they believe the country ought to “stand on its own two feet” will loom larger than the locations of U.S. nuclear weapons.”
I argue that forward deployed US tactical nuclear weapons (i.e. non-strategic B61s) are particularly poor barometers of commitment because their exploding sustainment/modernization costs could soon force their retirement. Moreover, they are no more credible than US strategic nuclear forces. Even if one assumes that lower-yield weapons might be more useable as counterforce weapons because they would cause fewer civilian casualties, a proposition I argued against in an earlier column, a reduction in yield is unlikely to reduce the significant political barriers to their use in the eyes of a US President. In others words, tactical nuclear weapons won’t strengthen the US willingness to come to an ally’s defense. Thus, they don’t add to the assurance value already provided by US strategic forces.
Re: extending deterrence from U.S. strategic forces, Jeffrey Lewis has suggested some creative ways to exhibit the role played by these weapons in the security of our East Asian allies. One option he offers would be to resume port visits by US ballistic missile submarines.
And yet there are very few conflict scenarios in which the US would be more likely to respond with nuclear weapons in the defense of an ally instead of conventional weapons. Again, this is not to suggest that nuclear weapons don’t play a role in reassurance. But nuclear weapons don’t on their own guarantee US commitment – far from it. As I note in my column, commitment is illustrated first and foremost by the strength of shared political and diplomatic relations. The more US interests are intertwined with allies, the more likely the United States is to come to their defense. Nuclear weapons are like two-dollars bills; they’re still in circulation but they don’t play much of a role in your wallet. I argue that dialogue and conventional security cooperation (the exact operationalization of which will differ depending on the ally) are more potent currencies of assurance given the threat environments faced by most allies.
At the same time, US security commitments should not be used by allies to engage in adventurous/aggressive behavior that could increase the risk of conflict. And the United States should expect allies to meaningfully share in the burden of their own defense. The fact that many US European allies (including in Eastern Europe) spend less than 2% of their GDP on defense does not constitute meaningful burden sharing.
Finally, a number of key US allies view missile defense as vital to their security. Some allies place great importance on cooperation with the United States on missile defense; others in addition are pursuing or have expressed interest in pursuing their own independent systems. Poland and Turkey are particularly interesting cases (see here and here, for example).
Missile defense cooperation with allies can be an effective means of alliance management, lead to the deployment of US troops on the territory of allies, and provide protection against some missile threats. However, both the United States and its allies must be mindful of the technical limitations of ballistic missile defense, the limits of defense against nuclear-armed missiles, and the threat posed by some defenses to stability with Russia and China. The greatest emphasis should be placed on defense against rogue state short- and medium-range conventionally-armed rockets and ballistic and cruise missiles, which also happen to comport with the missile threats currently faced by most allies.