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.

Under the Umbrella: Nuclear Crises, Extended Deterrence, and Public Opinion

“…For example, the Japanese public has for decades remained strongly opposed to nuclear weapon use given the Hiroshima and Nagasaki legacies (Tanaka 1970;Baron, Gibbons, and Herzog 2020). In contrast, amid high tensions with Pyongyang, studies have shown the majority of South Koreans are interested in developing their own nuclear weapons even if they trust the nuclear umbrella (Ko 2019;Sukin 2020a;Son and Yim 2021). In the United States, reactions to Trump's criticism of the North Atlantic Treaty Organization, the United Nations, and the Trans-Pacific Partnership revealed many Americans are skeptical of international obligations (Pew Research Center 2017).…”

Japanese Public Opinion, Political Persuasion, and the Treaty on the Prohibition of Nuclear Weapons

“…Our work thus builds on a growing body of political science literature using survey experiments to assess public opinion on critical nuclear issues (e.g. Press, Sagan, and Valentino 2013;Sagan and Valentino 2017;Aronow, Baron, and Pinson 2019;Haworth, Sagan, and Valentino 2019;Ko 2019;Baron and Herzog 2020;Rathbun and Stein 2020;Sukin 2020;Koch and Wells Forthcoming).…”

The Nuclear Fuel Cycle and the Proliferation “Danger Zone”

“…Of course, I still 11 It is also important to note differential public opinion on nuclear proliferation in Japan and South Korea. While research shows that a majority of South Koreans support the idea of their country developing nuclear weapons (Ko 2019;Sukin, forthcoming), this is not the case in Japan. Polling indicates that 75% of the Japanese public wants the Abe administration to join the Treaty on the Prohibition of Nuclear Weapons (Baron, Gibbons, and Herzog 2020).…”

“…Today, some observers fear that weak US assurances might drive South Korea to proliferate in the face of an aggressive North Korea (Debs and Monteiro 2018). Recent survey-based studies have even shown that more than half of the South Korean population supports nuclearization (Ko 2019;Sukin, forthcoming).…”