Despite the end of the Cold War more than two decades ago, the U.S. still deploys nuclear weapons in several countries. But does deploying these weapons act as a deterrent to conflict, making these countries safer? In new research which analyses the effects of such nuclear deployments, Matthew Fuhrmann and Todd S. Sechser find that their presence does little, when compared with alliance guarantees. They write that having an alliance with a nuclear armed ally is actually more effective in preventing armed conflicts than the local deployment of the weapons themselves.
In 1962, Soviet leader Nikita Khrushchev deployed nuclear missiles on the island of Cuba, provoking the most dangerous international crisis since World War II. Khrushchev’s gambit brought the United States and the Soviet Union to the brink of nuclear war, but his decision to send nuclear forces abroad was hardly anomalous. At the time of the Cuban missile crisis, the United States had already deployed nuclear forces to Italy, Morocco, the Philippines, Turkey, West Germany, and other countries. As the Cold War progressed, both superpowers, along with Great Britain, sent nuclear bombs to more than 20 countries.
Foreign nuclear deployments are by no means relics of a bygone era. Even today, the United States has nuclear bombs on the territory of five European allies: Belgium, Germany, Italy, the Netherlands, and Turkey. And there is some talk of deploying American nuclear forces to Eastern Europe and South Korea in response to emerging nuclear threats from Russia and North Korea.
The prevalence of nuclear deployments raises an important question: does sending nuclear forces abroad protect allies and make the world a safer place?
Many scholars and policymakers believe that stationing nuclear forces abroad promotes peace through extended deterrence. Putting nuclear forces on an ally’s territory, according to this view, sends an important message about the strength of the alliance. A nuclear power that undertakes this effort shows that it is more committed to defending its ally, and more willing to fight on its behalf. This commitment, in turn, ought to dissuade potential aggressors.
We put this logic to the test in recent research (ungated version available here). Our analysis tells a different story: extended deterrence hinges on alliance guarantees, not on the presence of an ally’s nuclear weapons.
Drawing on declassified documents and other historical sources, we identified every publicly-known foreign nuclear deployment between 1945 and 2000 – totaling 23 in all. We used this new data to find out whether states that hosted foreign nuclear weapons were less likely to be attacked than other countries.
Our analysis revealed that nuclear deployments have been less useful for extended deterrence than many people believe: during the period we studied, deploying nuclear weapons on an ally’s territory had no effect on the likelihood that the ally would be attacked. While many countries that hosted nuclear weapons were never attacked, the same was also true for many countries that did not host them, as Figure 1 illustrates. In the end, the difference between the two groups was statistically negligible.
Figure 1 – Nuclear Deployments and the Risk of Attack
However, this doesn’t mean that alliances – or nuclear weapons – are unimportant for deterrence. Quite the contrary: our study found that having a nuclear-armed ally is one of the best ways to deter attacks. Indeed, alliances involving nuclear powers were far more effective at promoting deterrence than run-of-the-mill military alliances. Achieving credibility in extended nuclear deterrence is difficult, and success is never guaranteed. But our findings suggest that security guarantees from nuclear states promote peace, even if they do not ensure success every time (see Figure 1).
These results lead to a surprising conclusion: despite being “scraps of paper,” public alliance commitments are even more effective than deploying nuclear forces abroad. Words, in this case, are as good as deeds.
From a policy standpoint, our findings question the use of future nuclear deployments to bolster the protection of U.S. allies in troublesome regions. The case for keeping American nuclear weapons in Europe is particularly weak. If history is any guide, defense commitments that rely on an offshore nuclear deterrent will be just as effective as sending bombs abroad.
This article is based on the paper ‘Signaling Alliance Commitments: Hand-Tying and Sunk Costs in Extended Nuclear Deterrence’, in the American Journal of Political Science.
Featured image: B-2 Spirit assigned to the 509th Bomb Wing. (U.S. Air Force photo/Senior Airman Kenny Holston)
Note: This article gives the views of the authors, and not the position of USApp– American Politics and Policy, nor of the London School of Economics.
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Matthew Fuhrmann – Texas A&M University
Matthew Fuhrmann is an associate professor of political science and Ray A. Rothrock `77 Fellow at Texas A&M University. He is the author of Atomic Assistance: How “Atoms for Peace” Programs Cause Nuclear Insecurity (Cornell University Press, 2012. His research focuses on the politics of nuclear proliferation.
Todd S. Sechser – University of Virginia
Todd S. Sechser is Associate Professor of Politics at the University of Virginia, and a former Stanton Nuclear Security Fellow at the Council on Foreign Relations. His research focuses on coercion and diplomacy in international politics. His research has been published in the American Journal of Political Science, International Organization, and other academic journals.
Professors Fuhrmann and Sechser are the coauthors of the book Nuclear Weapons and Coercive Diplomacy, under contract with Cambridge University Press.