The global security architecture is undergoing profound structural shifts, characterized by a major conventional war in Europe and a rising potential for armed conflict in regions like East Asia. Amid these changes, the United States is increasingly viewed by some of its allies as a less reliable security guarantor. This shifting landscape has highlighted a puzzling trend in global security: nuclear-armed powers seem to lack a coherent understanding of the purpose of their arsenals. As strategic capabilities are increasingly built around conventional weaponry, nuclear deterrence has frequently failed to prevent major conflicts—a phenomenon described by expert Rose Goettemoeller as “The Strange Defeat of Nuclear Deterrence.” Consequently, regional powers face a growing paradox, feeling a heightened pressure to acquire their own nuclear weapons.
South Korea finds itself at the center of this acute dilemma. North Korea continues to expand its nuclear stockpile and has forged a significant alliance with Russia. Simultaneously, Pyongyang has formally renounced unification and designated South Korea as its primary enemy. These developments, combined with the fact that the continental United States is now within range of North Korean intercontinental ballistic missiles, have cast doubt on Washington's readiness to defend its regional allies. The resulting anxiety has sparked an intense debate within South Korea regarding the acquisition of its own nuclear weapons.
On July 27, retired Lieutenant General Chun In-bum published an article in the Korea Times outlining a sophisticated proposal for South Korea's nuclear path. Under Chun's plan, Seoul would acquire and own a nuclear weapons arsenal, but this capability would be embedded within an integrated deterrence network with the United States. This arrangement would mirror the "dual-key" systems deployed in Europe during the early Cold War, requiring the joint consent of both the host country and the United States before any weapons could be launched. However, Chun acknowledged that such a proposal would introduce major hurdles regarding the Nuclear Non-Proliferation Treaty (NPT), international verification, and complex decision-making processes.
While public opinion surveys in South Korea indicate up to 80 percent support for acquiring nuclear weapons, the country's policy elites remain far more cautious. Analysts and policymakers express concern over the potential damage to the U.S. alliance, South Korea's commitments under the NPT, and the severe economic consequences of proliferation. Instead, many elites favor establishing a "threshold capacity," which would allow South Korea to maintain the technical capability to rapidly develop nuclear weapons without actually doing so, provided the alliance with the U.S. remains stable.
Efforts to bolster nuclear deterrence on the Korean Peninsula could take several paths, including redeploying U.S. tactical nuclear weapons to South Korea to signal resolve to North Korea, China, and Russia. Historically, the deployment of U.S. nuclear weapons in Europe occurred alongside the development of independent deterrents by Britain and France. However, those arsenals emerged during a different era when the strategic confrontation with the Soviet Union dominated global security, and the U.S., unable to prevent their development, chose to integrate them into its European security posture.
Any proposed nuclear arrangement faces the classic strategic dilemma of "entrapment or abandonment." Host nations want effective extended deterrence but fear being dragged into a nuclear conflict without their consent. Conversely, the United States wants to avoid being pulled into a nuclear war initiated by an ally. Chun’s proposed dual-key system does not resolve this tension. If the U.S. retains escalation control, it essentially holds a veto, which may not satisfy South Korean security concerns. If South Korea is granted independent launch authority, the U.S. risks being drawn into a nuclear exchange against its will.
The practical difficulties of such joint military arrangements are illustrated by the two-decade-long negotiations over transferring wartime operational control (OPCON) of South Korean forces from the U.S. to Seoul. OPCON transition requires highly sophisticated and coordinated intelligence, communication systems, interoperability, training, and close coordination between commanders. A joint nuclear decision-making framework would be vastly more complex, involving the U.S. president under extremely tight decision windows dictated by regional geography. Ensuring both the prevention of unauthorized launches and the credibility of the retaliatory threat would present immense challenges.
A South Korean nuclear arsenal would also severely complicate the regional security environment. It could prompt Russia to increase its technological and military support to North Korea, particularly regarding nuclear delivery and control systems. Beijing would likely view a South Korean nuclear capability as a direct threat to its own security. This dynamic was demonstrated in 2016 when Seoul's decision to deploy the U.S. THAAD ballistic missile defense system triggered severe political and economic retaliation from China. The dispute was only partially resolved when then-President Moon Jae-in promised no further THAAD deployments and pledged not to integrate South Korea into a regional, U.S.-led missile defense network. A nuclear weapons program would likely provoke an even harsher reaction from Beijing, including severe economic sanctions, increased military deployments, and the potential retargeting of Chinese nuclear forces toward South Korea. It could also reignite the nuclear debate in Japan, triggering wider regional proliferation.
The impact on North Korea is equally difficult to project. While a South Korean nuclear deterrent might enhance overall deterrence against a nuclear attack, it could also drive Pyongyang to accelerate its efforts to build secure nuclear capabilities capable of striking the U.S. mainland. Furthermore, it would not necessarily deter low-level, non-military provocations below the threshold of open conflict.
Additionally, abandoning the NPT would carry immense reputational and legal costs. It would alter the international narrative, transforming South Korea from a democratic state operating under international law into a nation that has walked away from its global commitments. Under Article I of the NPT, the U.S. would be legally prohibited from transferring nuclear weapons or providing any nuclear assistance to South Korea. This would immediately jeopardize the 2015 "123 Agreement," which governs civil nuclear technology cooperation between Washington and Seoul.
While Chun’s dual-key proposal is unlikely to become official policy in the near term, alternative stabilization measures remain viable. These include integrating U.S. nuclear and conventional forces into joint operational planning, establishing formal nuclear consultation bodies, and improving early warning, intelligence sharing, and missile defense coordination. However, if South Korea ultimately decides it can no longer rely on the U.S. security umbrella, developing an independent nuclear deterrent remains an option—though one that carries the risk of international isolation, the potential collapse of the U.S. alliance, and a significantly more hostile security environment.
