Do Nuclear Alliances Create Nuclear Allies or Prevent Proliferation?
About the author: Lauren Sukin is a Ph.D. candidate in the Political Science Department at Stanford University.
How does the alliance between a client state and its nuclear ally influence the probability that the client state chooses to proliferate? The literature on this question primarily looks at one mechanism through which nuclear allies have often tried to reassure client states about their security — nuclear security guarantees. These guarantees state that the nuclear ally is willing and prepared to use nuclear weapons to come to the client state’s aid if they face a severe security threat. A crucial characteristic of these guarantees is their credibility, or the degree to which it is believed that the nuclear ally will actually follow through on its promises. The commonly accepted theory linking nuclear security guarantees to the risk of proliferation is the “credibility hypothesis,” which posits that support for nuclear weapons acquisition is low when a nuclear security guarantee’s credibility is high and vice versa.
However, my research offers a new theoretical approach. I posit that, under conditions of highly credible nuclear security guarantees, support for nuclear weapons acquisition should actually increase. This is because, as the credibility of a nuclear security guarantee increases, individuals become more concerned about unjustified or unfair use of nuclear weapons by their ally. This leads individuals in the client state support nuclear weapons acquisition in order to regain control over their nuclear fate.
To adjudicate between these two theories, my project designs and analyzes a survey experiment among a representative sample of adults in South Korea in order to assess how the perceived credibility of a security guarantee from a nuclear-armed ally (in this case, the United States) influences public preferences about proliferation. Survey respondents were presented with a high-credibility security guarantee, a low-credibility security guarantee, or control condition and were then asked about their support for nuclear weapons acquisition.
Ultimately, I find support for the unwanted use hypothesis, identifying a treatment effect whereby high-credibility nuclear security guarantees increase support for proliferation by between 2.60 and 4.87 percentage points.[1] These findings challenge the consensus of the credibility hypothesis’ approach to nonproliferation strategies by nuclear-armed states.
Ultimately, this project will provide a deeper understanding of alliance credibility in order to determine the conditions under which nuclear states can foster nonproliferation efforts in their allies. With the current turmoil on the Korean peninsula, an improved nonproliferation strategy could be vital to the U.S. ability to contain nuclear ambitions in South Korea and, ultimately, to promote the peaceful resolution of the ongoing nuclear crisis on the Korean Peninsula. Moreover, this research could be replicated and extended in other regions or with other types of alliances. For example, a revitalized investigation of the consequences of alliance credibility could have meaningful implications for the U.S. relationships with diverse non-nuclear allies, such as Germany, Japan, Taiwan, and Saudi Arabia. An increased U.S. capability to promote nonproliferation among its allies would offer a significant contribution to mitigating the risk of nuclear use worldwide.
[1] These findings come from comparisons between the high-credibility treatment group and the control treatment group.
