The causes and consequences of nuclear proliferation have received a great deal of
academic attention. However, nuclear weapons are rarely discussed in isolation in policy
circles. Instead, nuclear weapons are relevant as part of a category of weapons of mass
destruction (WMDs) that includes chemical and biological weapons (CBWs). Are the
factors that drive CBWs proliferation similar to those that drive nuclear proliferation?
What is the relationship between these weapons types? In this article, we explore
whether nuclear weapons and CBWs serve as complements or substitutes. Using newly
collected data on both CBWs pursuit and possession over time, we find that nuclear,
biological, and chemical weapons generally function as complements at the pursuit stage.
In addition, countries that acquire nuclear weapons become less interested in pursuing
other types of WMDs and are even willing to give them up in some cases.