Don’t be taken aback if one of the hottest issues for South Korea’s upcoming presidential election is nuclear weapons—more specifically, the need for South Korea to possess its own. While North Korea has refrained from nuclear weapons testing since 2017, the progress they demonstrated in the past has moved the nuclear debate to the forefront of South Korean society. This year, Kim Jong-un’s remarks about strengthening the Democratic People’s Republic of Korea’s (DPRK) nuclear arsenal delivered at the recent Eighth Party Congress was enough for South Korean conservatives to once again stand in favor of developing their own nuclear weapons. With the South Korean presidential election in March 2022 quickly approaching, political discourse in Seoul about nuclear armament is a trend not to be ignored by the U.S. government.

Hawkish voices in favor of nuclearization in South Korea are not new. Since 2006, the year of DPRK’s first nuclear test, the South Korean public and right-leaning politicians have consistently voiced concerns about South Korea’s national security in the context of an unpredictable and nuclear North Korea. Key members of leading conservative parties over the years have often cited the tenuous credibility of America’s extended deterrence and the asymmetrical security environment on the Korean Peninsula—with the Republic of Korea (ROK) only possessing conventional weapons—as reasons to pursue nuclear options. Such options range from the redeployment of U.S. tactical nuclear weapons, a “NATO-style” nuclear-sharing agreement with the United States, or even an indigenous nuclear arsenal. 

In the past, U.S. nuclear experts have been hesitant to acknowledge ROK’s nuclear debate as part of the mainstream global political discourse. However, recent statements from leading conservatives in Seoul show that the idea of a nuclear-armed ROK has evolved from a fringe argument to now potentially a serious component of the conservative party platform. Last month, Yoo Seung-min, a former member of the National Assembly and one of People Power Party’s (PPP) presidential candidates, proclaimed, “it is unrealistic to prevent us from our own nuclear armament when North Korea has not given up its nuclear weapons yet.” This month, Assemblyman Hong Joon-pyo, another PPP presidential candidate, argued in a recent Facebook post that North Korea’s continuing nuclear developments have South Korea on the verge of “becoming its nuclear slave,” unless ROK pursues a “NATO-style nuclear-sharing policy to correct the inter-Korean nuclear imbalance.”

Low approval ratings of Moon Jae-in’s administration since 2020 and PPP’s victories in the recent mayoral elections for Seoul and Busan, the two largest cities in South Korea, reflect the current political climate in ROK. It consists of a dissatisfied South Korean public with the liberal government and an opposition party leveraging such sentiment to its advantage. The recent mayoral results and current polls may not offer any definite outlook into the outcome of the upcoming presidential bout, but they do preface a competitive contest between the ruling Democratic Party and the opposing PPP, whose leaders champion a dangerous pro-nuclear policy. 

Whichever of three nuclear options the country may pursue, the harms of a nuclear ROK outweigh the potential benefits. While the presence of nuclear weapons may provide South Korea a sense of security against the North, it is also likely to make nuclear weapons a permanent reality on the Korean Peninsula. In fact, a South Korea with nuclear weapons plays into Pyongyang’s view of a hostile and imprudent Seoul, fueling tensions in the region. Furthermore, North Korea is likely to view a South Korean indigenous nuclear program as a pretext for further strengthening its own nuclear capabilities.

In addition, ROK’s nuclear armament complicates the continued goal of achieving denuclearization of the Korean Peninsula, a key concept throughout decades of engagement with DPRK. Past negotiations have delivered key documents on denuclearization, including the 1992 Joint Declaration, the 2005 Six-Party Joint Statement, the Panmunjom Declaration, and the Singapore Summit Joint Statement in 2018. North Korea embraced these agreements with the understanding of denuclearization of the Korean Peninsula as a reciprocating, two-way streak of both North and South Koreas committing to a nuclear zero. If ROK decides to nuclearize, then North Korea will have one less reason to honor such arrangements and start disarming.   

A nuclear South Korea is also likely to upset the U.S.-ROK alliance, a relationship already strained with several points of tension. Such pressure points include Moon’s impatient push to expedite the transfer of operational control authority in wartime (OPCON) to the ROK military, postponement of joint exercises for political reasons, and the broadening scope of the U.S.-ROK military cooperation on a strategy for the Indo-Pacific region and relations with China. Therefore, a new administration pursuing nuclear armament may come off as a sign of distrust toward the United States extended deterrence and by extension, a U.S.-ROK alliance already burdened by recent challenges. In pursuit of a “better” security guarantee, South Korea may ruin its current security guarantee.  

If the Biden administration continues to show a lack of diplomatic progress with Pyongyang, then the conservatives’ call for nuclear weapons for a “safer” ROK will not simply fade away.   

In order to better assure America’s ally about its extended deterrence, the Biden administration needs to re-examine the current deterrence arrangements and modify it to better address the changing security environment on the Korean Peninsula and East Asia as a whole—before South Korea takes matters into its own hands.

William Kim is a researcher at the Stimson Center’s 38 North Program. A graduate of Boston College, he has previously worked with Congressman Adam Smith and the House Armed Services Committee.