I. The Return of Trump and Reignited Nuclear Debate in South Korea

Upon his return to office, U.S. President Donald Trump flaunted his rapport with Kim Jong Un, referring to North Korea as a “nuclear power.” This remark has reignited the ongoing debate over nuclear armament within South Korean political circles (Sung 1/22/2025). The argument advocating for South Korea to pursue its own nuclear weapons, which already enjoys substantial support, has gained additional momentum following Trump’s re-election. Major media outlets have featured in-depth interview series discussing the necessity of South Korea’s nuclear armament as part of their New Year’s coverage (Yoon 1/14/2025).

Public opinion polls conducted by the East Asia Institute (EAI) well reflect this notable shift in public sentiment. While 58.5% of South Koreans supported nuclear armament in 2023 following the adoption of the Washington Declaration, this figure increased to 71.4% by August 2024. Regression analysis attributes this change primarily to two factors: (1) the growing nuclear threat posed by North Korea in 2024, exemplified by Kim Jong Un’s rhetoric regarding the “annihilation of the Republic of Korea,” and (2) escalating public skepticism about the reliability of the U.S. nuclear umbrella (Kim 2024).

This commentary examines the underlying assumptions driving the rapidly expanding debate on nuclear armament in South Korea: (a) that nuclear weapons are unique in their power, rendering conventional weapons’ superiority ineffective, and (b) that possessing a small-scale nuclear arsenal can address security concerns. Specifically, it explores how the security threat posed by a state like North Korea, with its limited nuclear arsenal, should be assessed. Additionally, it also addresses the implications of South Korea pursuing nuclear armament to achieve direct nuclear balance with North Korea. These issues are examined through the lens of “first strike capability” and “second strike capability,” as well as Carl von Clausewitz’s theory of “absolute war” and Robert Jervis’s concept of the “nuclear revolution.”

II. Core Assumptions of the Nuclear Armament Argument: Even a Small-Scale Nuclear Arsenal Can Provide Enough Deterrence

The growing advocacy within South Korea for nuclear armament highlights several key arguments for why the country must develop its own nuclear capabilities (Cheong 2023; Kelly and Kim 2024). First, proponents argue that the “possibility of achieving North Korean denuclearization through negotiations is slim,” and that there are “clear limitations to countering nuclear threats with conventional military means.”

Second, while North Korea continues to advance its nuclear capabilities, concerns about the credibility of the U.S. extended deterrence have intensified, particularly with the onset of the second Trump administration. If North Korea achieves its intercontinental ballistic missile (ICBM) capability that can directly strike the U.S. mainland, public confidence in the U.S. extended deterrence will further erode. This concern is compounded by the transactional nature of the Trump administration, which has sought to reduce security commitments to allies, thereby rending South Korea’s reliance on the U.S. nuclear umbrella increasingly uncertain.

Third, North Korea faces significant structural constraints in times of war, including a lack of sustained warfighting capability, vulnerability to combined airpower from South Korea and the U.S., and its limited territorial size that restricts the possibility of retreat. These factors suggest that a decisive defeat in a singular conventional warfare could pose an existential threat to the North Korean regime, thereby increasing the likelihood that Pyongyang might resort to a preemptive nuclear strike in dire circumstances.

Based on these arguments, advocates assert that South Korea’s conventional weapons are insufficient in countering North Korea and that acquiring nuclear weapons is the only way to ensure the country’s national security. On top of this, they claim that such a move would alleviate the U.S. defense burden on the Korean Peninsula while allowing the U.S. to allocate its strategic assets to counter threats from China and Russia, ultimately serving broader American interests. Furthermore, given North Korea’s nuclear capabilities, proponents believe that South Korea’s possession of approximately 100 nuclear weapons would significantly contribute to maintaining peace and stability on the Korean Peninsula.

III. The Vanity of Unsurvivable Nuclear Weapons: Insights from Clausewitz and Jervis

To evaluate the validity of the arguments advocating for South Korea’s independent nuclear armament, it is instructive to examine the evolution of the U.S.-Soviet nuclear competition during the early Cold War. This discussion is grounded in Clausewitz’s On War, which introduces the concept of “interactions in absolute war,” and Jervis’s The Meaning of the Nuclear Revolution, which addresses the notion of “mutual vulnerability.”

1. Clausewitz’s Three Interactions and the U.S.-Soviet Nuclear Competition: First-Strike Capability, Second-Strike Capability, and Mutual Assured Destruction (MAD)

The U.S.-Soviet nuclear arms race in the 1960s and 1970s aligns with the three interactions of “absolute war” outlined by Clausewitz (1873): “utmost use of force,” “aims to disarm the enemy,” and “utmost exertion of powers.” The principles underlying nuclear strategy—first-strike capability, second-strike capability, and MAD—are intimately tied to his explanation of the dynamics of escalation and the interaction of force. Just as Clausewitz argued that “friction” and the practical constraints encountered on the battlefield inevitably transform absolute war into real war, with political elements intervening in the dynamics of war, the decade-long intensification of the U.S.-Soviet nuclear arms race eventually culminated in the initiation of bilateral nuclear arms reduction negotiations by the 1970s.

First-strike capability not only refers to “a strike that was not only the opening volley of a nuclear war, but also directed against the nuclear capability of the enemy with the intention of crippling his means of retaliation” (Freedman 2003, 128). It is the ability to launch a preemptive strike that destroys the enemy’s nuclear capabilities, rendering retaliation impossible. This aligns with Clausewitz’s first two interactions: “utmost use of force” and “aims to disarm the enemy.” A state possessing first-strike capability could “compel one’s opponent to fulfill their will” by destroying its military forces and industrial bases. This dynamic leads strategists to regard nuclear weapons as the ideal tool of national strategy. However, this ideal state only existed briefly, from 1945 to 1949, when the U.S. held a nuclear monopoly.

The U.S. nuclear monopoly ended when the Soviet Union acquired second-strike capability, which is a “force capable of ensuring effective retaliation even after absorbing an enemy first strike” (Freedman 2003, 128). The key lies in securing the survivability of strategic assets, even after a nuclear attack from the adversary. Following the Soviet Union’s successful development of nuclear weapons, both superpowers embarked on an arms race to secure second-strike capabilities, leading to the development of underground silos and submarine-launched ballistic missiles (SLBMs). By the 1970s, the Soviet Union began to match the U.S. in ICBM and SLBM capabilities. Although the U.S. and the Soviet Union theoretically achieved MAD by both maintaining second-strike capabilities capable of guaranteeing each other’s total destruction, uncertainty about whether their current weapons systems could reliably ensure adequate retaliatory power led to a prolonged competition. This exemplifies Clausewitz’s “utmost exertion of powers.”

Even superpowers, however, could not sustain an “open-ended process” of nuclear arms racing. As the Soviet Union caught up with U.S. multiple independently targetable reentry vehicle (MIRV) technology, President Richard Nixon and General Secretary Leonid Brezhnev signed the Anti-Ballistic Missile (ABM) Treaty in May 1972 and initiated the Strategic Arms Limitation Talks (SALT) in Moscow, marking the first steps toward arms reduction (Freedman 2003). The culmination of the “utmost exertion of powers” by both sides resulted in the establishment of MAD, a state in which neither side could eliminate the other’s second-strike capability. As predicted by Clausewitz’s theory, political considerations reemerged once the military competition reached a point where second-strike capabilities became unassailable.

2. Jervis’s “Nuclear Revolution” and Its Preconditions: Establishing Mutual Vulnerability

The U.S.-Soviet nuclear competition escalated dramatically through Clausewitzian interactions during the 1960s and 1970s, before transitioning into a period of détente in the latter decade. The mechanisms driving this shift can be better understood through Jervis’s concept of the “nuclear revolution” and “mutual vulnerability” (Jervis 1989, 1–43).

Nuclear weapons possess unparalleled destructive power, capable of threatening the survival of an adversary’s society and population within a short timeframe. Consequently, there can be no “winner” in a nuclear war. The only viable strategy to ensure national security is to deter the use of nuclear weapons by imposing costs on an adversary that far exceed any potential benefits they might gain. Drawing on Glenn Snyder’s research, Jervis categorizes deterrence into two types. Deterrence by denial is to prevent the attacker from achieving its objectives by neutralizing the potential gains of aggression. Deterrence by punishment seeks to discourage aggression by threatening massive retaliation that imposes unacceptable costs on the attacker.

Deterrence by denial can theoretically be achieved in two ways: (1) through first-strike capability, which preemptively neutralizes an adversary’s nuclear arsenal, or (2) through strategic defensive systems like the Reagan administration’s Strategic Defense Initiative (SDI), which aim to intercept and neutralize incoming missiles. Historically, however, first-strike capability was only feasible during the U.S. nuclear monopoly era, while missile defense systems capable of achieving a 100% interception rate remain undeveloped and unlikely in the foreseeable future. This leaves deterrence by punishment, ensuring credible second-strike capability, as the sole viable strategy.

When two competing states gain credible second-strike capabilities, a “balance of terror” emerges, wherein the fear induced by each side’s nuclear arsenal is offset by the equal fear of retaliation. This balance functions analogously to an exchange of hostages: it can only be leveraged while the hostages are alive, but can be terminated if the consensus is violated. Therefore, MAD, which is made possible by possessing mutual second-strike capability, requires both parties to have the capacity to inflict the complete destruction of the enemy’s citizens, while such deployment should be refrained from.

Jervis argues that the foundation of the nuclear revolution lies in the shared mutual vulnerability resulting from both sides possessing reliable second-strike capabilities. This mutual vulnerability was the primary reason the United States and the Soviet Union engaged in a political strategy centered on this balance, rather than relying on conventional military superiority. He further asserts that when both sides possess credible second-strike capabilities, revolutionary effects emerge, including peace, the preservation of the status quo, and a reduced frequency of conflicts.

Therefore, nuclear revolution only operates under specific conditions: both parties must have survivable nuclear forces capable of retaliating after a first strike. These forces must be able to inflict unacceptable levels of damage on the adversary under any circumstances. Not all nuclear assets need to survive; rather, as long as “some part of a force” remains intact despite an enemy's nuclear attack, it creates the effect that “all of the force is invulnerable” (Waltz 2009, 402). In this sense, “a weapon that can hurt only people, and cannot possibly damage other side’s striking force, is profoundly defensive.” (Schelling 1960, 233). Paradoxically, weapons capable of causing greater destruction of human lives tend to promote peace and stability, while systems designed to neutralize nuclear arsenals often foster war and instability.

A critical challenge in maintaining the balance of terror lies in the innate uncertainty of war: until a nuclear conflict actually occurs, it is impossible to guarantee that one’s nuclear forces can survive and retaliate effectively. The development of a nuclear-powered submarine capable of deploying SLBMs armed with nuclear warheads could facilitate the maintenance of a highly stable state of MAD, much like the stability maintained by the U.S. and the Soviet Union during the Cold War. However, advances in anti-submarine warfare (ASW) and AI-enhanced autonomous weapon systems, such as precision underwater drones, could threaten the survivability of SLBM-based second-strike forces.

Due to this uncertainty, the balance of terror had to be “respected” among states engaged in nuclear competition (Freedman 2003, 195). A “consensus” on the balance of second-strike capabilities between these states was essential, and maintaining this balance was crucial. This is why missile defense had become the primary focus in nuclear arms reduction discussions between the U.S. and the Soviet Union. If this tacit agreement were disrupted, the states would inevitably find themselves compelled to re-enter a nuclear arms race. For example, while China maintained a modest nuclear arsenal of approximately 200–300 warheads for decades, it has rapidly expanded its stockpile in recent years, reaching an estimated 500 warheads in 2024 and aiming for 700–1,500 warheads by 2035 (Kristensen, Korda, Johns, and Knight 2024).

In short, nuclear competitors have historically shifted from the “utmost exertion of powers” to a stability based on MAD, as the further accumulation of nuclear capabilities no longer altered the balance of terror. This indicates that without credible second-strike capabilities, political negotiations are unlikely to occur. The prolonged nature of this competition—strategic bombers, qualitative and quantitative missile advancements, nuclear defense systems, and ASW capabilities—remains unavoidable until both sides achieve a consensus on the balance of nuclear power that must be mutually respected.

IV. The Misconception of Nuclear Armament: The Futility of Small-Scale Nuclear Arsenal Development

The various benefits cited by proponents of nuclear armament in South Korea—such as preventing nuclear war on the Korean Peninsula, addressing diminished trust in U.S. extended deterrence, enhancing South Korea’s autonomy and diplomatic stature, alleviating anxiety over North Korea’s nuclear threat, and reallocating resources to social welfare and education—cannot be realized through the development of a small number of nuclear warheads alone. These outcomes can only be realized if a mutually agreed-upon nuclear balance with North Korea is established and maintained stably.

However, ensuring the survivability of nuclear weapons to maintain credible second-strike capabilities entails immense costs. For instance, hardening missile silos and aircraft hangars to protect nuclear delivery systems, concealing these systems to evade detection (e.g., SLBMs and transporter erector launchers (TELs)), and stockpiling redundant assets to ensure survivability despite an adversary’s attack are all projects requiring national budgets on the scale of trillions of won (Congressional Budget Office 2021). Moreover, unlike the U.S. or the Soviet Union, South Korea’s small territory poses a significant challenge to constructing and maintaining second-strike capabilities (Lieber and Press 2017).

China, which has entered a nuclear arms race with the United States, possesses approximately 500 nuclear warheads and an almost fully developed nuclear triad in terms of delivery capabilities. Nevertheless, China continues to expand its nuclear arsenal at a rapid pace, underscoring the immense challenge of achieving credible second-strike capabilities against an overwhelmingly nuclear-capable United States. In comparison, North Korea, with its limited territory, underdeveloped delivery systems, and an estimated stockpile of only about 50 nuclear warheads (SIPRI 2024), is far from achieving credible second-strike capabilities against the United States. Thus, arguments suggesting that the U.S. would not trade San Francisco for Seoul, or that South Korea must pursue its own nuclear armament to counter North Korea’s advancing capabilities, are not grounded in realistic analysis.

Moreover, the assumption that gaining approval from the Trump administration would somehow make the costs of nuclear development negligible for South Korea, or that the period of instability and high costs during the initial nuclear development phase would be short-lived, is a highly irresponsible claim. Choosing the path of independent nuclear armament over U.S. extended deterrence would place the two Koreas in a direct nuclear arms race. Until both sides achieve mutually agreed-upon levels of second-strike capability, they would inevitably undergo a prolonged period of “utmost exertion of powers,” as Clausewitz described.

Whether this competition would end with 100 warheads, escalate to 1,000 warheads, or reach a compromise over a specific balance in nuclear delivery systems is entirely uncertain. During this period, there is a significant risk of unintentional escalations leading to all-out military conflict or even a nuclear war, making it difficult to ensure stable progress toward a new equilibrium. This uncertainty underscores why the development of a small nuclear arsenal is unlikely to provide a definitive solution to South Korea’s security concerns or to stabilize the broader geopolitical situation on the Korean Peninsula.  

References

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Congressional Budget Office. 2021. “Projected Costs of U.S. Nuclear Forces, 2021 to 2030.” May 21. https://www.cbo.gov/publication/57240. (Accessed: January 24, 2025)

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Sung, Ji-won. 2025. “Revitalized Support for Nuclear Armament with Trump’s ‘Nuclear State’ Remarks… Hong Joon-pyo, Na Kyung-won and Yoo Seung-min Call for ‘Nuclear Balance’ (in Korean).” Joongang Daily. January 22. https://www.joongang.co.kr/article/25309417. (Accessed: January 24, 2025)

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Yoon, Keunyoung. 2025. “South Korea Capable of Manufacturing 3 to 6 Nuclear Bombs Every Year … Can Surpass North Korea within Five Years (in Korean).” Yonhap News. January 14. https://www.yna.co.kr/view/AKR20250105013200546?section=search&sit=mappinghyperlink.(Accessed: January 24, 2025)

■ Yang Gyu KIM is the Principal Researcher and Executive Director at EAI, and a Lecturer in the Department of Political Science and International Relations at Seoul National University.

■ Translated and edited by: Jisoo Park, Research Associate; Sheewon Min, Research Associate
    For inquiries: 02 2277 1683 (ext. 208) | jspark@eai.or.kr