Publisher's Synopsis
This essay explores the connection between security guarantees and nuclear proliferation by allies of great powers. I propose a model to explain why U.S. allies pursue nuclear proliferation. I assert that this movement toward nuclear weapons occurs when an ally perceives that the U.S. defense commitment has become insufficient for the threat environment. I test this model using a case study of South Korea's exploration of nuclear weapons in the 1970s. South Korea was facing a severe threat environment when US President Richard Nixon announced that US allies would need to take greater responsibility for their own security. In response, South Korea began to explore a nuclear weapons program. In this context, South Korea's leaders interpreted the United States' attempt at alliance burden-shifting as a sign of abandonment. This perception tilted the threat-commitment balance out of alignment and led to forward movement toward nuclear proliferation. From this case and model, I conclude that US allies take steps advancing nuclear weapons activity when their perception of their threat environment outweighs their perception of US security commitment. From this conclusion, I draw implications about the role of presidential rhetoric and military force posture in assure US allies and discouraging nuclear proliferation.This compilation includes a reproduction of the 2019 Worldwide Threat Assessment of the U.S. Intelligence Community.During the 2016 US presidential campaign, then-candidate Donald Trump made comments alluding to his potential reorientation of US foreign policy. He indicated that he was considering reducing the United States' security commitment to US allies around the world. He also expressed an openness to nuclear proliferation by US allies, South Korea and Japan. These two statements together with the "America First" theme of his inauguration speech and his recent canceling of the Trans Pacific Partnership all indicate a general expectation that Asian allies must do more for their own security. This rhetoric echoes a previous period of US retrenchment in Asia. In 1970, US President Richard Nixon announced that US allies would need to take greater responsibility for their own security. In response, South Korea began to explore a nuclear weapons program. This period of uncertainty and its effects on nuclear proliferation may have lessons for today's policymakers. Regardless of whether President Trump implements a strategic redirection, it is useful to understand the dynamics that drive nuclear proliferation by a dependent ally. Would a reduction in US commitment to its allies lead to new or resumed nuclear weapons programs? How important are security commitments to containing nuclear proliferation? How does the US credibly signal commitment?
