Protection States Trust?: Major Power Patronage, Nuclear Behavior, and Alliance Dynamics

Why do some states that receive a nuclear security guarantee move towards, and sometimes back away from, nuclear weapons? To answer these questions, I propose alliance compensation theory. I argue that allies become more likely to engage in nuclear behavior when they doubt the reliability of the security guarantees they receive from their major power patrons (e.g., the United States and the Soviet Union. Specifically, I show that allies evaluate the strength of these guarantees by referring to their patron's overseas conventional military deployments and foreign policy doctrines -- in short, its strategic posture. When the nuclear-armed patron implements undesirable conventional military redeployments (e.g., unilateral troop withdrawals), the ally loses confidence in the patron's earlier pledges to provide it with military support in a future nuclear crisis. These doubts encourage the ally to adopt policies that range from signaling an interest in an nuclear arsenal to activating a nuclear weapons program. Allies that covertly undertake nuclear activities are seeking to produce an independent deterrent. Allies that overtly engage in nuclear behavior are also bargaining over the terms of their patron's security guarantees. I further argue that the interaction of two variables -- the ally's economic and security dependence on the patron -- affect the major power's ability to force the ally to credibly renounce nuclear weapons acquisition. To test this argument, I include three main cases on West Germany, Japan, and South Korea in addition to narrower cases on the United Kingdom, France, and Soviet allies. I also draw on statistical analysis to investigate the relationship between conventional military withdrawals and the likelihood of US allies to engage in nuclear behavior.