Proliferation and International Crisis Behavior

The literature on international conflict is divided on the impact of nuclear proliferation on state conflict. The optimists' argument contends that nuclear weapons raise the stakes so high that states are unlikely to go to war when nuclear weapons enter the equation. The pessimists rebut this argument, contending that new proliferators are not necessarily rational and that having nuclear weapons does not discourage war but rather makes war more dangerous. Focusing on one observable implication from this debate, this article examines the relationship between the severity of violence in crises and the number of involved states with nuclear weapons. The study contends that actors will show more restraint in crises involving more participants with nuclear weapons. Using data from the International Crisis Behavior (ICB) project, the results demonstrate that crises involving nuclear actors are more likely to end without violence and, as the number of nuclear actors involved increases, the likelihood of war continues to fall. The results are robust even when controlling for a number of factors including non-nuclear capability. In confirming that nuclear weapons tend to increase restraint in crises, the effect of nuclear weapons on strategic behavior is clarified. But the findings do not suggest that increasing the number of nuclear actors in a crisis can prevent war, and they cannot speak to other proliferation risks.