Credible Nuclear Security Commitments Can Backfire: Explaining Domestic Support for Nuclear Weapons Acquisition in South Korea

Abstract

How does the alliance between a client state and its nuclear ally influence support for proliferation in the client? Conventional wisdom suggests that when nuclear security guarantees are not credible, support for proliferation will be high, since a domestic nuclear capability offers an alternative source of deterrence. I introduce a new theory, which posits that highly credible security guarantees can backfire by causing some individuals to fear their ally might miscalculate—either by using nuclear weapons in an unnecessary preventative attack or by precipitous escalation of a crisis or conflict. Survey experiments conducted among representative samples of South Korean citizens in 2018 and 2019 support this theory, showing that increases in the credibility of the US nuclear security guarantee lead to increased support for nuclear proliferation among South Korean respondents.