Nuclear Weapons and Low-Level Military Conflict

Abstract Do nuclear weapons deter low-level military conflict? Although the political effects of nuclear weapons have been debated for more than seventy years, scholarship has yet to produce a clear answer. We design a study that reduces the risk of omitted variable bias relative to prior research. Our analysis compares the rates of conflict among eventual nuclear powers in the periods before and after they obtained an arsenal. We include two-way fixed effects to control for time-invariant state-specific confounders and address common shocks. Our findings indicate that switching from nonnuclear status to a nuclear arsenal decreases the risk of being targeted in militarized interstate disputes (MID) by nonnuclear challengers. However, when it comes to low-level conflict, nuclear powers do not appear to be deterred from instigating disputes with other nuclear-armed states. This result stands in contrast to most prior studies, which conclude that the possession of nuclear weapons increases or does not reliably decrease the risk of being targeted—even for nonnuclear challengers. Although there are clear limits to the deterrence benefits of nuclear weapons at low levels of conflict, states can reduce their vulnerability to some degree by developing a nuclear arsenal.