One of the most commonly discussed factors driving South Korea’s nuclear weapons debate is South Korean questioning of U.S. defense commitments. Commentators argue that given North Korea’s ability to threaten the United States with nuclear weapons, South Korean doubts over de-coupling and whether the United States would trade “Seoul for LA” have increased. However, a 2022 poll conducted by Seoul National University shows that 70.6 percent of surveyed South Koreans believe that the United States will come to the defense of South Korea, in contrast to the 26.3 percent who believe that the United States will abandon its security commitments in favor of national interests. Furthermore, support for the U.S.-South Korea alliance and confidence in U.S. defense pledges have not experienced any drastic reductions despite the increasing public favorability for nuclear weapons acquisition.
The current debate in South Korea can be viewed as a direct reflection of the emerging narrative that only South Korean actions, solutions, and independent capabilities can reliably resolve the North Korean threat and achieve stability on the peninsula. This idea reflects South Korean desires to have agency over their own security and is thus shaped by factors beyond U.S. credibility concerns, including: threat perceptions and policy options toward North Korea; perceived gaps in South Korean indigenous conventional capabilities; geopolitical developments shaping a new nuclear age; the weakening influence of normative restraints; and nationalist sentiment.
There are two ways in which North Korea influences the South Korean public debate over nuclear weapons. First, advancements in North Korea’s military capabilities have altered the South Korean public’s threat perception toward North Korea. In 2022, North Korea test-launched cruise, ballistic, and submarine-launched missiles from diverse launch sites and delivery systems. South Korean experts note that North Korea has moved beyond the development phase of its nuclear weapons program and is now in a new operational and verification phase of prioritizing the diversification, miniaturization, and deployment of its weapons arsenal. Furthermore, the September 2022 North Korean nuclear law has codified the elements of preemption and offensive readiness, adding to the broader threat that North Korean nuclear weapons pose.
Nuclear proponents in South Korea argue that the nuclear doctrine should be viewed as a North Korean declaration of victory since the outlined conditions of nuclear first use allow North Korea to both utilize its nuclear weapons as a coercive tool and possess an “absolute advantage” in the arms race between the two Koreas. As North Korea works to reduce the inter-Korean power asymmetry through advancements in both conventional and nuclear capabilities, South Korean perceptions of its increasing vulnerability to a North Korean attack will continue to drive arguments for an indigenous nuclear weapons program.
Second, broader South Korean public sentiment that the denuclearization of North Korea is unfeasible has led to calls for a change in policy toward the north. South Korean assessments of prospects for denuclearization and hopes for successful dialogue are at their lowest point in decades. This has led to calls for the abandonment of a denuclearization-focused policy toward North Korea and a shift to a policy of nuclear balance, with experts even arguing that only nuclear balance can achieve mutual denuclearization.
The perceived unlikelihood of North Korea abandoning its nuclear weapons program has contributed to the growing influence of arguments that the United States and South Korea must confront reality, acknowledge that past efforts to denuclearize North Korea have failed, and accept North Korea as a nuclear weapons state. With denuclearization no longer viewed as a realistic policy objective, especially in the short term, the South Korean public increasingly views strengthening South Korea’s defense posture and deterrence as its first defense priority, justifying arguments for a more aggressive approach to ensure peace on the Korean Peninsula.
Gaps in Conventional Deterrence
The next factor relates to a South Korean belief that its conventional deterrence and defense capabilities are insufficient against the increasingly sophisticated nature of North Korea’s weapons program. The Yoon Suk-yeol administration has revitalized the implementation of the “Three-Axis System” as South Korea’s primary response mechanism against North Korean attacks in order to bolster South Korea’s conventional deterrence.
However, gaps in the credibility and reliability of the three axes – Kill Chain, Korea Air and Missile Defense (KAMD), and Korea Massive Punishment and Retaliation (KMPR) – have led to concerns over South Korea’s ability to effectively demonstrate its conventional deterrence. South Korean specialists note that holes in missile defense systems, recent malfunctions involving offensive strike capabilities, and insufficient missile stockpiles indicate the lacking and compromised nature of South Korea’s conventional deterrence. Meanwhile, North Korea continues to advance both its missile and nuclear capabilities, leading a number of South Korean analysts to conclude that conventional deterrence is insufficient in properly addressing North Korea’s conventional and nuclear threats.
South Korean perceptions of its lagging capabilities, particularly as North Korea accelerates its military modernization, will likely fuel arguments for investing in nuclear capabilities as a means to overcome gaps in conventional deterrence. While U.S. capabilities provide both conventional and nuclear deterrence, South Korean assessments of its ability to deter a North Korean attack primarily focus on its independent capabilities, reflecting a desire for a more self-reliant and autonomous defense posture in which South Korea does not entirely depend on an external actor for its defense and survival.
Perceptions of a New Nuclear Age
Geopolitical developments have shaped the so-called “new nuclear age” both on the Korean Peninsula and globally. This age has been driven by national insecurities, expanding nuclear uncertainties, and the enhanced geopolitical role of nuclear weapons. If North Korea’s prioritization of intercontinental ballistic missile (ICBM) capabilities to strike the United States was reminiscent of the first nuclear age in which countries focused on developing strategic nuclear weapons, a new nuclear age informs North Korea’s current focus, which South Korean analysts note involves tactical nuclear weapons intended to directly target South Korea.
Furthermore, South Korean experts highlight the new era’s trilateral nuclear competition between the United States, China, and Russia as a factor that drives accelerated military modernization and increases the risk of nuclear consideration. In an age of unpredictable nuclear usage and weakening nuclear taboo, a growing number of South Koreans believe only the possession of nuclear weapons can properly prepare the country for the unpredictability and instability that will follow North Korean possession of both tactical nuclear weapons and ICBM capabilities.
This new nuclear age also stems from geopolitical developments involving Russia and China, North Korea’s closest allies. The war in Ukraine has led some in the South Korean public to argue that only the possession and presence of nuclear weapons can deter an invasion, believing that a nuclear-armed Ukraine would not have been invaded in the first place. The perceived similarities between South Korea and Ukraine both facing a nuclear neighbor who relies on nuclear threats to prevent U.S. involvement – despite the fact that South Korea is a U.S. treaty ally and Ukraine is not – have lent credence to South Korean arguments that it must develop a self-reliant defense strategy consisting of nuclear weapons. For South Korean analysts, the war has also indicated the difficulties of overpowering a nuclear-armed country with conventional capabilities and carrying out an all-out offensive under the threat of nuclear escalation.
In addition to the Ukraine factor, South Koreans are paying attention to China and a potential Taiwan contingency. There have been parallels drawn between Taiwan and South Korea as both being targeted by nuclear-armed countries with historical and revisionist aims toward reunification. In particular, nuclear proponents in South Korea have noted that Taiwan is a case study of whether deterrence can be successful without nuclear weapons. A Chinese invasion of Taiwan would have serious implications for both North Korea’s revisionist ambitions on the Korean Peninsula and the strategic calculus of South Korea’s nuclear weapons debate.
Weakening Normative Restraints
The two primary normative elements that have traditionally constrained South Korean nuclearization are the 1992 Joint Declaration on the Denuclearization of the Korean Peninsula and the NPT. However, the questioning of South Korea’s commitment to both agreements has weakened normative restraints and removed the taboo that previously labeled serious and high-level discussions of an indigenous nuclear weapons program as fringe or extremist.
Signed in 1992, the Joint Declaration on the Denuclearization of the Korean Peninsula outlines the commitment of both North and South Korea to not “test, manufacture, produce, receive, possess, store, deploy, or use nuclear weapons.” While calls to scrap the agreement have been present ever since North Korea tested its first nuclear weapon in 2006, South Korea has continued to uphold the principle of denuclearization outlined in the 1992 declaration as a valuable norm underlying the goal toward peace and stability on the Korean Peninsula.
However, South Korea’s commitment to the agreement has come under increased pressure as a greater number of voices, including Interim Chief of the ruling People Power Party Chung Jin-suk, have called for the scrapping of the agreement if North Korea were to conduct its seventh nuclear test. The belief that only South Korea is tied to the principle of denuclearization, despite North Korea’s blatant disregard for the agreement, continues to test the strength of this normative restraint.
Alongside the 1992 declaration, the Nuclear Non-Proliferation Treaty has served as the main global agreement constraining South Korean nuclear armament. Any South Korean argument to develop nuclear weapons has been most strongly opposed by critics pointing to the likely consequences that would follow a unilateral South Korean decision to leave the NPT, including sanctions by the international community and potential damage to the U.S.-South Korea alliance. Although Seoul’s commitment to the NPT remains the greatest normative restraint, an increasing number of voices are calling for the country to exercise its right to withdraw.
Nuclear proponents argue that the sophisticated and offensive nature of North Korea’s nuclear program now explicitly threatens South Korea’s survival, meeting the conditions outlined by Article Ten of the NPT that allows the withdrawing country to avoid international sanctions. While the Yoon administration has thus far maintained the country’s commitment to the NPT and the principle of global nonproliferation, it is likely that supporters of a nuclear South Korea will continue to call for the government to invoke Article Ten to formally withdraw, testing the effectiveness and persuasion of the NPT to restrain South Korea’s nuclearization.
Lastly, nationalist sentiment has also contributed to the active and widespread nature of the debate, albeit to a lesser degree throughout this year. The argument that has most captured proponents is that North Korea holds South Korea “hostage” with its nuclear weapons. Hong Joon-pyo, mayor of Daegu and former leader of the conservative party, has even likened the South Korean people to “slaves under North Korea’s nuclear blackmail.” Thus, nuclear weapons are viewed as a necessary tool to weaken North Korea’s perceived advantage in military capabilities and ability to control South Korean actions through nuclear provocations or coercion.
While South Korean conventional capabilities exceed those of the north, supporters of nuclear acquisition argue that such capabilities do not have the same “political and psychological effects” as nuclear weapons. As North Korea continues to conduct provocations and South Korea believes its response options are narrowing, the argument for South Korea to possess nuclear weapons to achieve unquestionable superiority against North Korea will likely gain prominence within the mainstream debate.
The South Korean debate over nuclear weapons development has garnered unprecedented attention and activity in response to changing peninsular, regional, and global dynamics. This paper has provided a holistic overview of the factors underlying the nuclear debate across a wide range of sources and voices in South Korea. However, it is important to note that the debate to date reflects various public perspectives that might influence South Korea’s future policy direction rather than a government-driven policy decision on nuclear development, despite President Yoon’s comment on South Korea’s nuclear option.
How the United States and South Korea cooperate within the alliance to jointly respond to such sentiments will be crucial in determining how the South Korean public views the opportunities and costs associated with nuclearization.
This piece was originally published on The Peninsula blog by the Korea Economic Institute.