Washington’s Cold Peace Is Seoul’s Hot Risk

A negotiated accommodation with a nuclear-armed North Korea may become unavoidable for the United States and South Korea. But an agreement is not the same as a stable order. The real test is whether diplomacy reduces risk for the alliance as a whole, rather than shifting the most dangerous parts of that risk from Washington to Seoul.

Before any major diplomatic opening, Washington and Seoul should jointly assess how changes in wartime operational control (OPCON), U.S. force posture, and diplomacy with Pyongyang interact, rather than allowing them to proceed as separate policy tracks. The allies also need a clearer agreement on the roles of the United Nations Command (UNC), Combined Forces Command, and South Korean authority before a crisis forces those questions into the open. 

Any nuclear bargain should also account for the broader security balance, including not only North Korean weapons transfers to Russia but also Russian technology, training, and battlefield experience flowing back to North Korea. A diplomatic settlement may reduce one category of threat without resolving the larger security problem. An agreement that reduces the threat to the American homeland while leaving South Korea with more responsibility but no commensurate reduction in danger would not be genuine de-escalation. It would be risk relocation. 

Seoul’s task, therefore, is to ensure that alliance adaptation does not become strategic decoupling. Close U.S.-Korea coordination must remain the foundation, while minilateral and multilateral institutions provide insurance when bilateral politics or universal mechanisms falter. The objective is not to dilute the alliance, but to keep authority, responsibility, and security aligned as circumstances change. For Seoul, that is the essential measure of a durable cold peace. Risk reduction must be shared, not transferred. 

Three Transitions at Once

The alliance is undergoing three transitions at once. The first is command. The Lee Jae Myung administration wants to accelerate the conditions-based transfer of OPCON. The second is force posture. The United States wants South Korea to assume more responsibility for deterring the North while giving U.S. forces greater flexibility for wider Indo-Pacific missions. The third is diplomacy. U.S. President Donald Trump remains interested in dealing directly with North Korean leader Kim Jong Un, while the Lee administration is encouraging another opening and pursuing a more engagement-oriented policy of its own. 

None is inherently destabilizing. OPCON transfer can strengthen South Korean agency; a revised division of labor can make the alliance more sustainable; and diplomacy may constrain parts of North Korea’s nuclear buildup or reduce the risk of miscalculation even if it cannot eliminate the threat. The risk lies in simultaneity. If command arrangements are changing while U.S. military roles are being redefined and negotiations with Pyongyang put exercises, deployments, or deterrence measures into play, responsibilities can shift before political and military expectations are clarified. 

A recent disagreement between South Korea and UNC is a small but revealing example of this synchronization problem. In mid-August, reporting revealed UNC plans to consolidate Joint Security Area security and Military Armistice Commission functions into a single brigade. The command described it as an internal reorganization with no added capability and said Seoul had been informed throughout, but South Korea’s Minister of National Defense Ahn Gyu-back said the next day that the two sides had agreed not to proceed. This development exposed an institutional question that will become more consequential as OPCON transition advances: who has authority over what, from armistice to gray-zone confrontation to war? 

The distinction matters because OPCON transition concerns the combined warfighting command: it does not eliminate UNC’s separate responsibilities under the Korean War Armistice Agreement. If the two arrangements evolve without being clearly reconciled, Seoul could assume expanded responsibility for wartime operations while the allies remain uncertain on the delegation of authority during the crisis that precedes war. 

That is the broader danger of the three transitions. Strategic decoupling need not result from a deliberate political decision. It can emerge from poorly synchronized transitions. Pyongyang need not break the alliance—it need only identify the moment when Washington and Seoul are least able to respond with a single political and military voice. That moment does not require a decision in Pyongyang so much as a date, and Kim Jong Un has the luxury of waiting for one.

Friction Is No Longer Confined to Security 

Simultaneous transitions create a timing problem, while cross-domain spillover creates an issue-linkage problem. U.S.-South Korea disagreements increasingly spill across policy domains. 

The Coupang dispute is illustrative of this. Seoul views its response to the company’s massive data breach as legitimate domestic enforcement, while some members of the U.S. Congress and other critics in Washington have portrayed it as discriminatory treatment of a U.S.-based firm. Seoul has insisted that the dispute should remain separate from trade, investment, nuclear cooperation, or security talks. Yet, the need to draw that boundary shows how difficult such separation is becoming.

Coupang is not comparable in strategic weight to OPCON or extended deterrence. The broader concern is the erosion of barriers between policy domains. In a more transactional Washington, disputes over tariffs, investment, technology regulation, defense burden-sharing, civil-nuclear cooperation, and security can spill over into one another and compound. Any one may be manageable; several at once can create “bilateral overload,” weakening political trust and making it harder to insulate core security cooperation from political friction. 

China and North Korea are likely to judge not each dispute in isolation, but the accumulation of disputes and what it reveals about alliance cohesion. Thus, the challenge is not simply to resolve individual disagreements, but to prevent them from spilling into critical security functions.

Seoul’s Own Blind Spot

The uncertainty reflects policy shifts on both sides of the alliance. In Seoul, the Lee administration has moved toward a more engagement-oriented, “peace first” approach while recalibrating the North Korea policy it inherited from its predecessor. On August 15, President Lee called for talks on replacing the armistice with a peace regime and for practical steps to halt further nuclear buildup. This approach reflects a real dilemma: sanctions have not produced denuclearization, but the absence of dialogue has not stopped North Korea from expanding its arsenal.

The problem is that dialogue without leverage is unlikely to change Pyongyang’s calculations. North Korea has so far rejected Seoul’s overtures while continuing to strengthen its military. Under these conditions, repeated reassurance or unilateral gestures may reduce tension at the margins, but they could also convince Pyongyang that pressure produces accommodation.

This is why strategic continuity matters. The Nuclear Consultative Group, strengthened extended deterrence mechanisms, and the institutional gains of Camp David, including deeper trilateral deterrence and security cooperation, should not be treated as partisan legacies of the previous conservative government. They are accumulated assets of the South Korean state and provide the leverage that makes diplomacy more credible.

That matters especially as Washington asks Seoul to carry a larger share of its own defense. If South Korea seeks more autonomy while weakening the institutions that underpin allied deterrence, it could bear a heavier burden while gaining less influence over U.S. decisions. Likewise, South Korea should not simply welcome renewed U.S.-North Korea negotiations without first defining the outcomes it can and cannot accept. Otherwise, it risks encouraging a process in which South Korean interests are discussed without sufficient South Korean influence. 

The choice, therefore, is not between deterrence and engagement. It is to ensure that deterrence gives engagement leverage, while engagement does not erode deterrence.

Institutional Insurance for the Alliance

These pressures make the case for institutional insurance. The U.S.-South Korea alliance must remain the anchor of South Korea’s security, but it should not be the sole channel through which every military, diplomatic, and economic shock must be managed. The answer is not to hedge away from Washington, but to reinforce the bilateral core with arrangements that preserve cooperation when political friction congests the alliance.

The first layer should be a more durable U.S.-South Korea-Japan framework. The Camp David mechanisms—missile-warning sharing, regular exercises, consultations, and economic-security cooperation—should be institutionalized so that they survive leadership changes in Washington, Seoul, and Tokyo. Pyongyang already treats the three countries as a strategic grouping. Their cooperation should therefore rest on routine institutions, not on the chemistry of individual leaders.

The second layer should more firmly connect Northeast Asian security to NATO’s Indo-Pacific partners and European democracies. Russia has already connected the European and Korean theaters through North Korean troops and weapons in Ukraine. South Korea should deepen cooperation with Japan, Australia, Canada, the European Union, NATO, and other democratic partners on cyber defense, defense production, maritime security, drones, technology protection, and sanctions implementation. The value of these networks lies not only in shared threats but also in shared rules, institutional habits, and political trust that can outlast individual governments. 

The third layer should turn multilateral monitoring into coordinated enforcement. The Multilateral Sanctions Monitoring Team (MSMT) has helped fill the monitoring gap left by the collapse of the UN Panel of Experts, but it cannot compel compliance. Seoul should connect its findings directly to coordinated action with the United States, Japan, Group of Seven (G7) members, and other capable middle powers on illicit finance, cyber theft, export controls, and Russian military-technology transfers to North Korea. 

The division of labor should be functional. The U.S.-South Korea alliance remains indispensable for deterrence, intelligence, and high-end military integration. In addition, minilateral coalitions can provide operational continuity and implementation capacity, while broader multilateral institutions contribute legitimacy, rules, and political reach. Such an architecture reinforces the alliance without requiring Washington to initiate or manage cooperation in every domain. Where interests and capabilities converge, Seoul should be able to organize collective action itself. 

A more resilient architecture should also give South Korea room for selective engagement with China without incorporating Beijing into the democratic security framework itself. Beijing supports Pyongyang, but it may not benefit from a North Korea that is less dependent on China, strengthened by Russian assistance, and increasingly effective at drawing the United States, South Korea, and Japan together. Seoul should test whether that divergence creates space for cooperation, particularly on crisis management and constraining North Korea-Russia military ties. The aim is not strategic trust with China, but bounded cooperation where interests overlap. 

Risk Reduction without Risk Transfer

A cold peace is not necessarily peace. It is a distribution of risk. 

That distinction matters as Washington again considers diplomacy with Pyongyang. President Lee has encouraged President Trump to pursue a phased approach that would initially freeze additional fissile-material production, prevent transfers, and constrain further long-range missile development while preserving denuclearization as a longer-term goal. 

There is logic to this approach. North Korea will not dismantle an expanding nuclear arsenal merely to enter negotiations. But the relevant question is not only whether a deal reduces risk. It is whose risk it reduces and where the remaining risk goes. 

A bargain focused on long-range nuclear missiles could make the American homeland safer while leaving largely untouched the shorter-range nuclear forces that threaten South Korea and Japan. At the same time, the 2026 U.S. National Defense Strategy calls on Seoul to assume “primary responsibility” for deterring North Korea, backed by “critical but more limited” U.S. support.

Each policy is defensible on its own. 

Together, however, they could produce asymmetric de-risking: Washington reduces the threat most dangerous to the United States while Seoul assumes greater responsibility for the threat that remains. The danger is not U.S. abandonment but strategic decoupling resulting from the interaction of otherwise reasonable policies. 

That possibility makes the problem larger than bilateral alliance management. Seoul must think not only about the strength of the alliance itself, but also about the institutional architecture that surrounds it.

Shin-wha Lee is Professor of Political Science and International Relations, Director of Korea University’s Institute for Interdisciplinary Unification Studies, and Former Ambassador for International Cooperation on North Korean Human Rights. The views expressed here are the author’s alone.

This material is distributed by KEI on behalf of the Korea Institute for International Economic Policy. Additional information is available at the Department of Justice, Washington, DC.