On Extended Nuclear Deterrence

Abstract

ABSTRACTThis analysis discusses the central challenges that countries face when they practice extended nuclear deterrence. One key problem has to do with credibility: potential aggressors may not believe that a country would fight to defend an ally, particularly if doing so risks a nuclear attack against its homeland. Countries might be able to address this issue by forging formal alliances with protégés or by stationing nuclear forces on the protégé’s territory. Do these measures discourage third-party aggression? Defence pacts involving nuclear-armed states effectively bolster extended deterrence. One risk of extending nuclear protection from the American perspective, however, is that it might pull the United States into unwanted wars by risk-acceptant protégés. Yet, in a nuclear context, the risk of alliance entrapment is generally overblown. Placing nuclear weapons on an ally’s territory does much less to bolster extended deterrence than one might initially think. Although foreign nuclear deployments may reassure allies and promote non-proliferation to some degree, their value for extended deterrence is fairly minimal. The United States continues to deploy nuclear weapons in five European countries, but the case for maintaining these deployments is decidedly weak.