Yongusil 103: Explaining S. Koreans’ Support of Nuclear Acquisition

By | October 18, 2021 | No Comments

US atomic weapons in South Korea, 1958 | Image: Wikipedia Video

In September, South Korea tested a submarine-launched ballistic missile (SBLM), making it the first country without nuclear weapons to do so. This comes amid further missile testing from North Korea, including ballistic missile testing. In addition, China recently tested a nuclear-capable hypersonic missile and has been constructing nuclear missile silos. The meaning and significance of these tests is a matter of debate, but these developments lead some to claim an arms race is afoot.

It should come as little surprise, then, that some in South Korea are calling for nuclear weapons on South Korean soil. Certain conservative figures have, over the last few decades, voiced concern about the United States’ deterrence capabilities and commitment in the face of a nuclear North Korea and a worsening security environment. In 2017, Hong Jun-pyo, the 2016 conservative candidate for South Korean president, argued that if Washington did not reinstate tactical nuclear weapons on the peninsula, Seoul would be forced to develop its own domestic nuclear option. Although this is an unlikely scenario, it enjoys rather robust public support. A 2017 Gallup Korea poll showed that 60 percent of South Koreans support their country developing nuclear weapons. This position certainly is not fringe, but many remain unconvinced of the seriousness of South Koreans support for nuclear proliferation.

Lauren Sukina PhD candidate at Stanford University’s Department of Political Science, pre-doctoral fellow at the Center for International Security and Cooperation, and soon-to-be Assistant Professor of International Relations at the London School of Economics and Political Science — shows that, contrary to expectations, South Koreans show strong support for a domestic nuclear option precisely because of the US nuclear security guarantee. This support persists despite the potential consequences of going nuclear. In this review piece, she summarizes her recent survey experiment on the matter. – Steven Denney, Managing Editor

The Backfire Effect of Nuclear Security Guarantees: An Explanation for South Koreans’ Support of Nuclear Weapons Acquisition

by Lauren Sukin

As South Korea continues to show interest in the development of dual-use technologies, such as precision missiles and nuclear-powered submarines, growing domestic support for nuclear proliferation has become an increasingly important phenomenon. Conservative South Korean politicians have openly advocated for an indigenous nuclear capability, while liberal politicians have expressed concerns about the consequences of reliance on US nuclear capabilities. What explains today’s high levels of support among South Koreans for the development of nuclear weapons?

The international relations literature traditionally teaches that nuclear security guarantees – such as the US promise to leverage its nuclear arsenal to defend South Korea from its nuclear-armed adversaries – can act as substitutes for nuclear arsenals in recipient states of these guarantees. From this perspective, the US nuclear security guarantee should reassure South Koreans that they do not need a nuclear capability in order to deter challenges to their security from North Korea and China. Given consistent US commitments to US-South Korean defense cooperation, the existing South Korean interest in nuclear proliferation may be puzzling.

Security Guarantees: No Substitute for Your Own | My research1)Lauren Sukin, “Credible Nuclear Security Commitments Can Backfire: Explaining Domestic Support for Nuclear Weapons Acquisition in South Korea,” Journal of Conflict Resolution 64, no. 6 (2020): 1011-1042. provides a new perspective on this issue. I argue that, contrary to the dominant consensus, security guarantees may not always be seen as substitutes for domestic security forces. Instead, they can backfire. This happens when promises of protection from nuclear states raise concerns about the willingness of the nuclear protector to initiate or escalate a conflict over its ally’s security. For example, the 2013 overflights of US B-52 and B-2 aircraft over South Korea fed crisis escalation fears. Similarly, President Donald Trump’s 2017 “fire and fury” rhetoric raised concern among South Korea’s politicians and public about the possibility that the country could become embroiled in a nuclear conflict involving the United States and North Korea. After all, South Koreans prefer conventional options2)Lauren Sukin, “Experimental Evidence on Determinants of Support for Nuclear Use in Response to Threats of Nuclear Retaliation,” Peace and Conflict: Journal of Peace Psychology 26, no. 3 (2020): 336-339.  in response to nuclear threats. These fears of entrapment in precipitous nuclear conflicts can drive recipients of nuclear security guarantees to distance themselves from their alliances and to seek independent sources of security. Nuclear proliferation can provide this security, as well leverage over the adventurousness of nuclear guarantors.

I examine the consequences of the credibility of nuclear security guarantees using two waves of survey experiments fielded in South Korea in 2018 and 2019. The evidence shows that nuclear security guarantees – though often intended as reassuring – can threaten allies. I find that credible US nuclear security guarantees increased South Koreans’ support for nuclear proliferation. In the 2019 survey, the baseline level of support for a domestic nuclear deterrent was 58 percent, in line with other polling that has shown robust public support for nuclear proliferation. In comparison, when told about a high-credibility nuclear security guarantee, where the United States would be very likely to use its nuclear weapons to respond to North Korean nuclear use against South Korea, support for proliferation increased substantially to 71 percent. Compared to the control group or to low-credibility guarantees, high-credibility guarantees in the face of North Korean nuclear or conventional attacks on South Korea increased respondents’ support for proliferation.

Moreover, informing respondents of the negative consequences of proliferation does not significantly reduce support. In the same 2019 survey, 72 percent of respondents who voiced support for proliferation maintained their support after being informed that sanctions would certainly result. The South Korean public is also aware that these costs are likely—76 percent independently anticipated sanctions to occur. The backfire effect of high-credibility nuclear security guarantees is thus not being driven by concerns regarding the cost of proliferation. Instead, credible nuclear security guarantees create support for nuclear weapons development in spite of the costs.

Unwanted Use Theory | What explains the counterintuitive findings of my research? Mediation analysis reveals support for my “unwanted use theory,” which holds that support for proliferation and a credible security guaranteed are positively related. Credible nuclear security guarantees backfire because many South Koreans want to avoid becoming caught in a US-driven conflict with North Korea. They see proliferation as a way to shift nuclear responsibility on the Korean Peninsula away from the United States.

Indeed, a majority of respondents believed that the United States would “bring South Korea into an otherwise avoidable conflict.” Proliferation was seen as a solution to the dangers of reliance. For example, when asked to explain their rationale behind supporting proliferation, some respondents answered:

“to prevent the United States from using South Korea”

“to contain the United States”

“[If we had nuclear weapons,] we would no longer have to be constantly mindful and wary of other major powers.”

The backfire effect is related to concerns that a nuclear guarantor will be overly risk tolerant when it comes to nuclear use. Thus it is opposition to nuclear weapons that drives the effect; those that do not want to use nuclear weapons to resolve security concerns are more afraid of relying on the United States and would prefer the South Korean government to have more leverage in the conditions under which nuclear weapons would be used. Indeed, 26 percent more respondents trusted the South Korean government to make responsible decisions with nuclear weapons than the US government. In addition, I find that respondents who oppose nuclear use are more likely to “backfire” against credible US nuclear security guarantees than respondents who would support the use of nuclear weapons.

Only a minority of South Koreans followed the logic of the conventional understanding of nuclear security guarantees, which views these guarantees as substitutes for nuclear proliferation. Yet the co-existence of both groups in the South Korean public — those who fear abandonment by the United States and those who fear that reliance will lead to unwanted nuclear use — creates dual-sided pressure for the South Korean government to consider nuclear proliferation. Both groups may view proliferation as a solution to South Korea’s alliance troubles. This research provides insight into possible sources of public support for nuclear proliferation in South Korea. It suggests, too, that further work is needed in understanding how elites will respond to and contend with calls for a domestic nuclear option.


1 Lauren Sukin, “Credible Nuclear Security Commitments Can Backfire: Explaining Domestic Support for Nuclear Weapons Acquisition in South Korea,” Journal of Conflict Resolution 64, no. 6 (2020): 1011-1042.
2 Lauren Sukin, “Experimental Evidence on Determinants of Support for Nuclear Use in Response to Threats of Nuclear Retaliation,” Peace and Conflict: Journal of Peace Psychology 26, no. 3 (2020): 336-339.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.