By George Hutchinson
The November 2025 U.S. National Security Strategy does not mention North Korea or the DPRK. South Korea appears, but largely within a broader call for U.S. allies to spend more on their defense and acquire the capabilities necessary to deter adversaries. Two months later, the 2026 National Defense Strategy made that call even more explicit. It states that “South Korea is capable of taking primary responsibility for deterring North Korea with critical but more limited U.S. support,” a shift the strategy directly links to “updating U.S. force posture on the Korean Peninsula.” The omission of North Korea from the NSS is not, by itself, a declaration of policy. Read alongside the NDS, however, it reinforces a clear strategic signal: Washington intends to shift greater responsibility for deterring North Korea to Seoul.
These strategic developments have naturally generated questions about the future of U.S. forces in Korea, the transfer of wartime operational control (OPCON), and the division of military responsibility between Washington and Seoul within the U.S.-ROK alliance. Against North Korea’s expanding nuclear arsenal and its recent “hostile state” turn toward South Korea, the shift in responsibility carries particularly significant implications. Yet viewed historically, the underlying problem is not entirely new. For more than five decades, the alliance has repeatedly adjusted the distribution of forces, authorities, and responsibilities as South Korean capabilities have grown and U.S. strategic priorities have changed.
Continuity, therefore, does not depend on a particular troop level, command relationship, or basing structure. It depends on preserving an effective combined defense framework through successive periods of adaptation. The architecture of deterrence on the peninsula has never required one permanent formula for who provides what. It has required that the pieces continue to fit in a way that preserves credible combined defense.
Responsibility and the Nixon Doctrine
An early example came during the Nixon administration. The Nixon Doctrine called on U.S. allies to assume a greater share of responsibility for their own defense as Washington reduced its military commitments in Asia. In a letter to President Park Chung-hee dated May 26, 1970, Nixon explained that the United States would honor the Mutual Defense Treaty while preparing to withdraw close to a third of the 63,000 U.S. forces then stationed in South Korea. Echoing language that would find its way into the 2026 NDS decades later, Nixon explained that South Korea’s economic and military capabilities had grown to the point where it could assume a larger share of the burden for its own defense. To compensate for the withdrawal, Nixon pledged a substantial five-year increase in military assistance and offered additional economic aid. By 1971, roughly 20,000 U.S. personnel had departed, including the entire U.S. Seventh Infantry Division.
The drawdown—one element of what would become known as the broader “Nixon shocks” of the early 1970s—heightened South Korean concerns about American reliability and contributed to Park’s decision to explore a clandestine nuclear weapons program. Yet, consistent with Nixon’s assurances, the reduction was not conceived simply as abandonment of South Korea. Washington coupled it with continued treaty commitments and support for modernization of the ROK armed forces. The underlying strategic challenge was already taking shape: how could South Korea shoulder greater responsibility without creating the perception—or reality—of a weakened alliance, or worse, an eroding U.S. commitment to its ally?
American force levels would continue to change thereafter, but legal constraints that did not exist in Nixon’s time have since been established. Congress first imposed statutory restrictions on reductions below 22,000 U.S. personnel in the FY2019 National Defense Authorization Act and subsequently raised the threshold to 28,500. Current law prohibits the use of authorized funds to reduce the approximate U.S. presence below 28,500, or to complete OPCON transition in a manner that deviates from a bilaterally agreed plan, until required certifications and assessments have been provided to Congress and a 60-day period has elapsed.
Headcount is therefore both politically salient and institutionally protected. But it remains an incomplete measure of alliance capability.
From Uncertainty to a More Integrated Command Structure
Changes in command arrangements provide another example of alliance adaptation. By the mid-1970s, the existing security structure faced significant pressure. Following the fall of Saigon, Kim Il Sung mounted a diplomatic campaign aimed at the U.S. military presence and United Nations Command. At the 1975 UN General Assembly, a North Korean-backed resolution calling for withdrawal of U.S. forces, dissolution of UNC, and replacement of the Armistice with a peace treaty passed by 54 votes to 43, with 42 abstentions. A competing resolution supported by Washington and Seoul also passed, but made termination of the UNC contingent on the establishment of alternative arrangements that would preserve the Armistice. The contradictory outcome frustrated Pyongyang’s immediate objective while leaving uncertainty over the future of the existing command structure.
The allies responded by strengthening other mechanisms of combined defense. At the annual U.S.–ROK Security Consultative Meeting in 1975, both sides agreed to consolidate a number of smaller exercises into “Team Spirit,” creating a new, large-scale annual training event that provided a visible demonstration of American commitment and helped alleviate concerns over a U.S. withdrawal.
Uncertainty increased after Jimmy Carter entered office committed to withdrawing U.S. ground combat forces. Presidential Directive/NSC-12 envisioned phased removal of U.S. Army brigades while retaining Air Force units, military assistance, and the Mutual Defense Treaty. Congressional opposition and changing assessments of the North Korean threat eventually caused Carter first to postpone and, in 1979, suspend the withdrawals.
Yet this period of apparent retrenchment also produced a more integrated alliance institution. In November 1978, the U.S.–ROK Combined Forces Command became operational, transferring operational control of designated U.S. and ROK forces from the UNC to a bilateral combined command. One of the alliance’s periods of greatest uncertainty therefore did not simply restore the structure that preceded it. It helped produce a new, more deeply integrated one.
Force Posture Is Not Synonymous with Force Presence
The end of the Cold War brought another adjustment. In April 1990, the Department of Defense proposed reducing the U.S. military presence in South Korea by 7,000 personnel—5,000 Army and 2,000 Air Force—as part of a broader transition from what the Department described as moving from a “lead role to a support role,” with additional phased reductions dependent on relations between Seoul and Pyongyang and improvements in South Korea’s military capabilities. While South Korea had provided some direct support for the stationing of U.S. forces since 1976, the end of the Cold War also saw formal cost-sharing begin under the Special Measures Agreement, signed on January 25, 1991.
As part of the drawdown, the Bush administration announced that U.S. Air Force operations would be shut down at three air bases in Korea, resulting in the 2,000-personnel reduction. That raised a practical question for the Air Force: if permanent U.S. presence declined, what infrastructure would still be required to receive and support forces during a contingency? The answer helped produce a March 1991 memorandum of understanding between the U.S. Air Force and Republic of Korea Air Force establishing five collocated operating bases at Suwon, Daegu, Cheongju, Gimhae, and Gwangju. The agreement defined a COB as a Korean air base without a permanently assigned USAF operational unit during peacetime. The arrangement emerged directly from the force-reduction environment while preserving wartime beddown capacity.
The point is that permanent presence could decline while reception capacity, infrastructure, and arrangements for reinforcement were preserved. In other words, force posture—the broader combination of capability, readiness, infrastructure, and supporting arrangements—is not synonymous with force presence. Troop numbers are the most visible measure of American commitment, but they do not by themselves capture what forces can be received, supported, integrated, and employed if circumstances change.
The creation of the COBs provides a notable historical echo. More than three decades before the 2026 NDS called for South Korea to assume “primary responsibility” with more limited American support, U.S. policy was already discussing a transition from a “lead role to a support role.” The circumstances differ considerably, but the recurring challenge is familiar: how to adjust responsibility while ensuring that reductions in permanent presence do not translate into diminished combined capability.
OPCON Transition Is Not a Strategic End State
The issue of operational control (OPCON) has moved along on a parallel track. On 1 December 1994, the ROK Joint Chiefs of Staff assumed peacetime—or armistice—OPCON over ROK forces, while Combined Forces Command retained wartime OPCON over forces designated to it. That adjustment to Korean authority did not replace combined defense; it changed how South Korean responsibility was carried out within it.
The allies have since pursued a conditions-based transition of wartime OPCON. That process has moved slowly and undergone repeated adjustment, but it has gained new momentum. President Lee Jae Myung has publicly reaffirmed his intention to complete the transition before his term ends in 2030 and has pressed for an earlier target. U.S. Forces Korea Commander General Xavier Brunson told Congress in April that USFK had delivered to the Pentagon a roadmap intended to meet the necessary conditions no later than the second quarter of fiscal year 2029—January to March 2029—while continuing to emphasize that the process remains conditions-based rather than calendar-driven.
The contemporary debate reflects different views of what the next command arrangement should do. Hanbyeol Sohn argues that maturation of the ROK military and changes in the strategic environment make OPCON transition a military imperative. David Maxwell agrees that the combined command structure must evolve but cautions against treating the transfer itself as the strategic objective. In his formulation, “Who commands?” matters, but the more consequential question is what kind of combined command can sustain deterrence, military effectiveness, escalation control, and alliance cohesion.
A historical analysis need not choose between them. Institutions built for one era can require redesign as capabilities and circumstances change. But changing the arrangement for wartime operational control is not itself the strategic end state. The relevant test is whether the functions that make combined defense credible—deterrence, military effectiveness, escalation control, and alliance cohesion—are preserved, and preferably strengthened, through the transition.
What the History Shows
Adjustment has not meant substituting South Korean responsibility for the alliance. It has meant changing how that responsibility is carried out within the alliance. Nixon reduced forces while preserving the bilateral defense treaty and strengthening ROK capabilities. The creation of CFC transferred operational control functions from the UNC to a more deeply integrated bilateral structure. The 1991 creation of the COBs reduced permanent Air Force presence while preserving wartime beddown. The 1994 OPCON decision increased South Korean peacetime authority while retaining wartime OPCON within the CFC. The 2026 NDS now calls for Seoul to assume primary responsibility for deterring North Korea while the United States provides critical but more limited support.
These adjustments should not be viewed as stations along a single track toward American disengagement. They arose from different circumstances: Vietnam-era burden-sharing, challenges to the UNC, Carter-era retrenchment, post-Cold War force reductions, growing South Korean military capability, and today’s changing U.S. strategic priorities in a multipolar world. What connects them is a recurring problem of design, not a story of departure.
When one variable moves—responsibility, operational-control arrangements, or forces—the others are affected. A reduction in force presence without a credible reinforcement plan and combined framework can raise doubts about commitment. An OPCON transition without matching interoperability and reinforcement arrangements risks becoming an institutional milestone rather than a military improvement. A posture redesign without a clear division of alliance responsibility leaves unanswered what the revised structure is intended to accomplish.
That challenge may soon become particularly acute. There are two significant alliance policy adjustments proceeding in parallel: greater South Korean responsibility for deterring North Korea and, following OPCON transition, a CFC commanded by a ROK general. Neither development requires predicting a future USFK troop number, but considering how the two would operate together is increasingly relevant.
The near-term test for the alliance will therefore be whether greater South Korean responsibility and a ROK-led post-transition CFC can be aligned with U.S. reinforcement, extended deterrence, interoperability, access and infrastructure, and the political credibility of American commitments. The November 2025 U.S.–ROK presidential fact sheet already pointed in that direction, coupling an enduring U.S. force presence and extended deterrence with South Korea’s commitment to strengthen the capabilities necessary to lead the combined conventional defense against North Korea.
The history does not show that every alliance adjustment was smooth or inevitable. Carter’s suspended withdrawal plan and the long delay in wartime OPCON transition demonstrate otherwise. It shows something more precise: combined defense on the peninsula has been preserved by adjusting the division of labor rather than freezing it.
The question in 2026 is therefore not whether the alliance should change. It always has. It is whether a new distribution of responsibility, a new arrangement for wartime operational control, and an evolving force posture will still add up to a combined defense that can be reinforced and believed. That is a more demanding standard than a troop number or a transfer date. It is also the only standard these adjustments, across the alliance’s history, have in common.
Dr. George A. Hutchinson is the Editor-in-Chief of the International Journal of Korean Studies and an adjunct professor at George Mason University’s Schar School of Policy and Government, where he teaches “Korea and World Order.” He is the author of North Korea’s Nuclear Decisions and Strategies: Sovereignty, Legitimacy, and the Bomb (Routledge, 2024) and Army of the Indoctrinated: The Suryong, the Soldier, and Information in the KPA (HRNK, 2022).
He currently supports Headquarters Air Force Futures wargaming. He previously served as Operational Energy Prototyping Lead in the Office of the Deputy Assistant Secretary of Defense for Energy Resilience and Optimization. Before that, he was a Senior Regional Planner advising on U.S. Air Force basing issues in the Republic of Korea and, in earlier Pentagon advisory roles, he specialized in wargaming and energy policy. A retired U.S. Air Force officer, Dr. Hutchinson served as a Logistics Readiness Officer, Northeast Asia Foreign Area Officer, and Korean linguist.
His writing has appeared in U.S. Naval Institute Proceedings, Air Force Journal of Logistics, Marine Corps University Press, the International Journal of Korean Studies, and reports by the Korea Economic Institute of America. Dr. Hutchinson holds a Ph.D. from George Mason University’s Schar School of Policy and Government and a Master of Science in Logistics Management from the U.S. Air Force Institute of Technology.
