Sharing the bomb: how foreign nuclear deployments shape nonproliferation and deterrence

What are the political and strategic consequences of nuclear deployments overseas? The United States continues to maintain around 200 nuclear warheads in Europe, and some observers have called for the United States to redeploy tactical nuclear weapons to the Korean peninsula. This article reviews the insights from recent research on the effects of foreign-deployed nuclear weapons. It asks two central questions. First, does the evidence support the view that foreign nuclear deployments contribute to deterrence? Second, do these deployments strengthen or undermine the Treaty on the Non-Proliferation of Nuclear Weapons? The evidence suggests that foreign nuclear deployments contribute less to deterrence than previously believed. Further, nuclear deployments probably have mixed effects on proliferation. Unanswered questions for further research include the extent to which nuclear-sharing arrangements reassure allies, and the political and strategic consequences of canceling them.