Does Nuclear Superiority Matter?

Feb 11 '13

The New York Times reports this morning that President Obama wants to renew his efforts to cut the U.S. nuclear arms arsenal. He is not proposing unilateral cuts. Yet, any cooperative agreement with Russia would result in a reduction of U.S. nuclear superiority versus Russia and (even more so) other states.

The conventional wisdom is that this doesn’t matter (see here for Robert Jervis’ classic statement). Having a larger nuclear stockpile beyond the point where you can assuredly destroy the opponent does not yield similar advantages as does having a larger conventional army.

I find the conventional argument persuasive but there are some counterarguments. In the most recent issue of International Organization (ungated version) my colleague Matthew Kroenig argues that in a crisis between two nuclear powers, the state that enjoys a nuclear advantage is willing to run more risk than its opponent. This gives the nuclear superior state greater “effective resolve,” meaning that the other state is less likely to think that the state with nuclear superiority will back down. Consequentially, states with nuclear superiority are more likely to prevail in crisis bargaining between nuclear powers. Kroenig then shows that there is indeed a correlation between nuclear superiority and emerging victorious in crises between nuclear powers.

This argument is controversial. The data set is small. Although Kroenig does a good job controlling for possible confounding factors, there really is no good way to draw causal inferences from data like this.  The same issue of International Organization contains an article (ungated version) by Todd Sechser and Matthew Fuhrman, who claim that nuclear weapons are of no use in increasing the credibility of threats to seize territory or another asset. Moreover, using nuclear weapons is costly. Thus, they find that while nuclear weapons are extremely useful for deterrence, they do little for “compellence” (making a threat to force an opponent to take some desired action). They show with a different data set of crisis bargaining that threats from nuclear states are not more likely to succeed than threats from non-nuclear states.

There are a host of other issues to consider, such as precisely what mix of nuclear capabilities to preserve in order to maintain effective deterrence. Given cuts in defense spending and President Obama’s stated agenda, I expect quite a bit of debate on this in coming months/years.

ps. Dan Nexon finds the fact that the premier journal in international relations publishes such contradictory findings in the same issue disconcerting:

 “[..]how are policymakers and non-academics to interpret such an exchange? The situation strikes me as unsatisfactory. If our mission is to prove that our work “matters” and thus, for example, deserves public funding… then, well, okay. But if our mission is to better shape policy, then what? Indeed, I suspect most “consumers” of this kind of debate will simply accept the position that fits with their prior commitments.

I accept the point but I do not know what the alternative is. This is not an issue about the state of the discipline but the difficulty (and importance) of the issue. There are reasonable theoretical positions on both sides and very limited data to help us discriminate between them. The Sechser and Fuhrman data set is a bit bigger than Kroenig’s but they also do not solve the causal inference issues; especially if Kroenig and Weintraub are right that nuclear imbalance deters states from entering conflicts in the first place. How can we do better than advocate for reasoned debates based on logic and assessments of the historical record (quantitatively and qualitatively)?