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The ROK-U.S. alliance stands at a critical inflection point, shaped by a transforming security environment, shifts in U.S. alliance strategy, and South Korea’s capability growth. Depending on how the alliance's vision is defined and how the roles and responsibilities of ROK and U.S. forces are realigned to realize that vision, the alliance can generate momentum to accomplish even greater tasks.

Based on a shared understanding of the alliance’s future direction amidst a changing regional security landscape, the ROK and the U.S. have begun consultations to strengthen the alliance’s capabilities and posture. Both sides are discussing the modernization of the alliance with the goal of rebalancing roles and responsibilities between U.S. and ROK forces on the Korean Peninsula while maintaining extended deterrence.[1]

The ROK-U.S. military alliance was established by the Mutual Defense Treaty signed on October 1, 1953. Over the past 70-plus years, the alliance has been decisive in maintaining peace on the Korean Peninsula through war deterrence. The alliance has also been integral to South Korea’s development into a top-10 economic power and a vibrant liberal democracy. Now evolving from a supported-asymmetric alliance to a reciprocal-symmetric alliance, the ROK-U.S. alliance must be readjusted to effectively address the changing strategic security environment.

Through this strategic perspective, this article first comprehensively assesses the security environment. It then identifies six core areas for the modernization of the ROK-U.S. alliance—alliance vision, expansion of the alliance’s roles, USFK’s strategic flexibility, ROK-U.S. wartime OPCON transition, the challenge of the North Korean nuclear program, and South Korea’s increase in defense spending—and discusses their current status and future direction.

I. A Comprehensive Strategic Assessment of the Security Environment

The ROK-U.S. alliance was forged to block the spread of communism in the crucible of the Korean War, instigated as part of the Soviet Union's “eastern detour strategy for global communization.” The alliance later joined forces in the Vietnam War while countering new forms of military threats from North Korea, including local provocations and terrorism. The Cold War ended with the collapse of the Soviet Union and the dissolution of Eastern European states. Although a U.S.-led liberal order seemed to take root, the 9/11 terrorist attacks in 2001 triggered international wars on terror in Afghanistan and Iraq. Following the 2008 global financial crisis, China's GDP surpassed Japan's in 2010, marking the beginning of U.S.-China hegemonic competition.

Today, the intersection of domestic political upheaval and international conflicts has led to ongoing armed conflicts across the globe, amplifying geopolitical tensions.

The series of events in South Korea, from the declaration of martial law on December 3, 2024, to the presidential election on June 3, 2025, was a triumph for Korean democracy. However, internal South-South conflicts, as well as divisions across regional, generational, gender, and class lines, pose a security challenge. Seoul’s North Korea and unification policies have been tumultuous under successive progressive and conservative administrations. Despite South Korea’s overwhelming superiority in nearly every sector of national capacity, North Korea is taking the initiative in the bilateral military dynamics.

North Korea's external strategy upholds regime survival and balanced diplomacy with China and Russia while advancing hostile policies toward South Korea and the U.S.[2] In a contingency, the North Korean military is likely to mount a surprise attack centered on asymmetric capabilities to create favorable conditions and conclude the war quickly. North Korea appears to be strategically leveraging the new Cold War. On June 18, 2024, North Korea and Russia signed a Comprehensive Strategic Partnership treaty, and North Korea has since dispatched 11,000 combat troops to the war in Ukraine, allowing its forces to gain experience in modern warfare. The possibility of Russian support in military satellite or ICBM re-entry technology, Russia’s assistance with Pyongyang’s construction of nuclear-powered submarines, and the guarantee of Russian military intervention pose direct threats to the ROK-U.S. alliance. Kim Jong Un has redefined inter-Korean relations not as kin, but as two hostile states engaged in war.[3] Pyongyang is encouraging a "great cataclysm" to annihilate the South. As of 2024, estimates show that North Korea possesses about 50 nuclear warheads and enough fissile material to produce approximately 90 more.[4] By 2027, it is projected to possess over 180 nuclear weapons and more than 10 ICBMs, threatening not only the Korean Peninsula but also the U.S. mainland.[5] Internally, the regime is tightening its grip on the populace through laws such as the Law on Rejecting Reactionary Thought and Culture (2020), the Youth Education Guarantee Law (2021), and the Law on Protecting the Pyongyang Cultural Language (2023), while facing systemic challenges from worsening economic pressures.

The resurgence of Donald Trump, under the slogan of "Make America Great Again" (MAGA), is shaking the global economic and security order. Xi Jinping's long hold on power, emphasizing "Socialism with Chinese Characteristics for a New Era," has not ruled out the use of force to occupy Taiwan. China is conducting large-scale military demonstrations and overtly pursuing an Anti-Access/Area Denial (A2/AD) strategy to seize maritime superiority. China is also establishing a Sino-centric global order in maritime, land, and digital sectors through its Belt and Road Initiative (BRI). The BRICS bloc is expanding its influence by strengthening solidarity among Global South nations and regional organizations.[6] The Chinese and European economies are stagnating, while the reorganization of global supply chains and tariff wars are underway. A new industrial revolution is dawning, driven by AI technology and AI-led industries. Meanwhile, global warming is causing tectonic shifts, pushing humanity toward existential threats.

In this new Cold War era of integrated geopolitics, the geopolitical center is shifting from Europe to Asia. Key actors are no longer just great powers but an integration of great and middle powers. Alliance dynamics are evolving from bilateral to multilateral security frameworks, and the link between Asian and European security is strengthening.[7]

The ROK-U.S. alliance must share threat perceptions, redefine its vision to build a peaceful and stable world, and realign the roles and responsibilities of U.S. and ROK forces to address new, complex security challenges.

II. Core Issues for Modernizing the ROK-U.S. Alliance

1. Alliance Vision

1) Contributions of the ROK-U.S. Alliance

To reform the ROK-U.S. alliance, we must first assess the contributions of the alliance over the past 70-plus years and examine its vision and strategic principles.

Forged through the bloody battles of the Korean War, the alliance was institutionalized by the ROK-U.S. Mutual Defense Treaty on October 1, 1953. To restore the Republic of Korea's territory and defend liberal democracy, the two states jointly made immense sacrifices. Korean casualties totaled 1,612,477 (137,899 military deaths, 373,599 civilian deaths, 450,741 military wounded, 680,367 civilian wounded, and over 420,000 military and civilian POWs, abductees, or missing). The U.S. suffered 129,514 casualties (33,643 deaths, 92,134 wounded, 3,737 POWs),[8] with over 4.85 million personnel serving throughout the war (2.83 million in the army, 1.60 million in the navy, and 0.42 million in the air force).[9]

After the war, the U.S. provided approximately $1.39 trillion in aid to South Korea until 1999.[10] Through technology transfers, imports of Korean goods, and sharing economic know-how, the U.S. enabled South Korea, once one of the world's poorest nations, to become the only country to transition from an aid recipient to a donor after the Second World War. Programs including the Fulbright Scholarship allowed young Koreans to study advanced science and technology abroad and return to contribute to national development. The economic value of the alliance, in terms of savings in defense spending from the USFK presence, is estimated to be double South Korea's annual defense budget.[11] Through direct and indirect intervention, the U.S. also constrained authoritarian regimes and helped instill the values of a free press, human rights, and the rule of law in Korean society.

The alliance has performed as a deterrent through USFK, the Combined Forces Command (CFC), and ROK-U.S. consultative bodies. The presence of USFK guaranteed U.S. intervention in the event of a North Korean invasion, treating it as a war against the U.S. itself. The CFC has contributed to deterrence by developing operational plans and demonstrating the deployment capabilities of U.S. reinforcements through various joint exercises. Consultative bodies like the annual Security Consultative Meeting (SCM) between defense ministers and the Military Committee Meeting (MCM) between Joint Chiefs of Staff chairmen have also contributed to deterrence through security assessments and threat management.[12]

On the other hand, the U.S.-led combined defense system fostered a sense of over-reliance on the alliance for security, causing dysfunctions such as an identity crisis for the ROK military and limitations on its operational autonomy.

2) Vision and Strategic Principles of the ROK-U.S. Alliance

The vision of the ROK-U.S. alliance is the denuclearization of the Korean Peninsula and the establishment of a peace regime, the institutionalization of security cooperation in Northeast Asia, and the construction of a global liberal international order.

Its strategic principles are as follows: First, the alliance is based on the core values of freedom, democracy, the rule of law, market economies, and human dignity. Second, the alliance guarantees strategic autonomy, enabling both nations to grow and develop through innovation and creativity. Third, the alliance aspires to become a reciprocal alliance. Fourth, it is an alliance where both nations fulfill their respective roles with a sense of duty and responsibility.

The future vision can be detailed across three levels. First, on the Korean Peninsula, the goal is denuclearization and the establishment of a peace regime. At the ROK-U.S. summit on April 26, 2023, marking the 70th anniversary of the alliance, the two leaders declared their support for "a unified Korean Peninsula that is free and at peace," committing to "build a better future for all Korean people."[13] The mission of the alliance is to realize a free, unified Korea. The emergence of a unified Korea would signify the civilizational end of the Cold War system. It would not only liberate 26 million North Koreans suffering from poverty and human rights abuses but also send a message of hope to failed states plagued by civil war and dictatorships. It could also serve as a catalyst for integrating Eastern and Western cultures into a global civilizational community. I propose the establishment of a presidential "ROK-U.S. Korean Unification Consultative Committee" to develop a vision and strategy for a unified Korea and translate them into policy.

Second, in Northeast Asia, the alliance will engage in confidence-building activities such as exchanges and cooperation with regional nations, exercising joint leadership to transform the regional order from one of conflict and confrontation to an order of cooperation and coexistence. These efforts include institutionalizing a Northeast Asian Security Cooperation Organization with the participation of South Korea, North Korea, the U.S., Japan, China, Russia, and Mongolia. It also involves creating a Northeast Asian Rapid Response Force—composed of military, medical, police, and NGO personnel—to jointly respond to regional disasters through Humanitarian Assistance & Disaster Relief (HA/DR) operations.[14]

Third, at the global level, the alliance will safeguard the liberal international order by contributing to peacekeeping operations, the non-proliferation of WMDs, counter-piracy operations, the protection of sea lines of communication, and cybersecurity.

2. Expanding the Roles of the ROK-U.S. Alliance

The preamble of the Mutual Defense Treaty states that an armed attack in the Pacific Area would be met jointly, and Article 3 declares that "an armed attack in the Pacific area on either of the Parties…would be dangerous to its own peace and safety and declares that it would act to meet the common danger in accordance with its constitutional processes."[15] Based on this principle of the alliance, South Korea's intervention is a natural obligation if a hostile state attacks a liberal ally in the Pacific, leading to an armed conflict with U.S. forces.

In the past, South Korea dispatched two combat divisions and a total of 325,517 personnel to the Vietnam War from 1965-1973, suffering 5,099 deaths and 11,232 wounded.[16] The deployment of the Zaytun Division to the Iraq War and the Ashena Unit to the Afghanistan War was also in keeping with the alliance principle.

In a scenario where China invades Taiwan and its carrier battle group attempts to control the first island chain, assets from the Jeju Fleet Command[17] could be deployed to intercept Chinese forces. ROK Marines, alongside the U.S. Marine Expeditionary Force in Okinawa, could participate in operations to thwart a Chinese landing on Taiwan.[18] These interventions must be conducted within a scope that does not compromise deterrence on the Korean Peninsula.

Should any liberal ally sharing our values be under attack, we must jointly respond to the aggression, whether the aggressor is China or Russia. At the Camp David Summit on August 18, 2023, the leaders of the ROK, U.S., and Japan pledged to "coordinate our responses to regional challenges, provocations, and threats."[19] To implement this commitment, they agreed in November 2024 to establish a Trilateral Coordinating Secretariat in Seoul.[20] I propose the operation of a "ROK-U.S.-Japan Trilateral Military Cooperation Task Force" composed of strategic planners and security experts from the ROK Joint Chiefs of Staff, the U.S. Indo-Pacific Command, and Japan's Joint Staff. Through simulated wargames based on scenarios of a war on the Korean Peninsula, in Taiwan, and a simultaneous two-front war, the roles and responsibilities of each country could be identified. Such activities would enhance deterrence and contribute to victory in the event of a contingency.

3. Strategic Flexibility of U.S. Forces Korea (USFK)

In a strategic dialogue on January 23, 2006, ROK Foreign Minister Ban Ki-moon and U.S. Secretary of State Condoleezza Rice agreed that "The ROK, as an ally, fully understands the rationale for the transformation of the U.S. global military strategy, and respects the necessity for strategic flexibility of the U.S. forces in the ROK."[21]

Traditionally, USFK has focused on the defensive mission of deterring North Korean military threats. However, in the current security environment, the Korean Peninsula and the Indo-Pacific region are organically linked, and major international issues like the U.S.-China strategic competition have cascading effects on the region. Accordingly, USFK's scope is expected to expand significantly to include pan-regional missions, such as participating in U.S.-led multi-domain operations in Taiwan, the South China Sea, and the East China Sea.[22]

This means USFK could be redeployed for military conflicts outside the Korean Peninsula in addition to managing North Korean threats. Regarding this expanded role, any "flow-out" of USFK forces to the Indo-Pacific should be a one-time deployment per event and should transit through U.S. bases in Japan. This would prevent the Korean Peninsula from being used routinely as a launch pad.[23]

Furthermore, just as F-35 fighter jets were rotationally deployed as backfill assets when a Patriot battery was recently redeployed to the Middle East,[24] an agreement must be reached with the U.S. to ensure that replacement forces are deployed before or simultaneously with any USFK flow-out.

Meanwhile, a reduction or withdrawal of USFK could be perceived as a weakening of the security commitment, potentially prompting aggression from North Korea or China. Therefore, it is undesirable to redeploy or withdraw USFK forces to Okinawa, Guam, or the Philippines. U.S. forces stationed on the Korean Peninsula, a strategic hub in Northeast Asia, play a crucial role in checking not only North Korea but also China and Russia. Amidst intensifying U.S.-China competition, the importance of USFK has only grown.

4. ROK-U.S. Wartime Operational Control (OPCON) Transition

Both the ROK and U.S. governments have a clear intention to pursue the wartime OPCON transition. The Trump administration's Interim National Defense Strategic Guidance states that the U.S. will focus on deterring a Chinese invasion of Taiwan and defending the U.S. homeland, while allies will take on most of the responsibility for deterring North Korea.[25] The Lee Jae Myung administration also intends to complete the OPCON transition within its term.[26]

The military must prepare for the worst-case scenario. The possibility of Xi Jinping and Kim Jong Un colluding to initiate two-front wars in Taiwan and on the Korean Peninsula cannot be ruled out. U.S. security experts suggest that in a two-front war, the U.S. would commit not only its forces in Japan and Guam but also USFK assets to the Taiwan theater, leaving South Korea to defend itself alone.[27]

In 2014, the ROK and U.S. defense ministers agreed to a Conditions-based OPCON Transition Program (COTP).[28] The three conditions are: 1) The ROK military secures the capabilities necessary to lead the combined defense; 2) The alliance secures the comprehensive capabilities to counter North Korea’s nuclear and missile threats; 3) The security environment on the Korean Peninsula and in the region is conducive to a stable OPCON transition.

In October 2018, to facilitate the OPCON transition, the two defense ministers agreed to establish a Future Combined Forces Command (F-CFC), with an ROK four-star general as Commander and a U.S. four-star general as Deputy Commander.[29]

As of August 2025, an assessment based on the COTP shows that Conditions 1 and 2 are met, while Condition 3 is yet to be fulfilled. Condition 1, the ROK military’s securing of critical military capabilities, is largely fulfilled across intelligence, operations, logistics, and communications. Condition 2, securing the alliance's essential capabilities against North Korea's nuclear threats, is met through the ROK's establishment of the Three-Axis System, the creation of a Strategic Command, and the development of ROK-U.S. Conventional-Nuclear Integration (CNI) operational plans. Condition 3, the regional security environment, still needs improvement.

A rushed OPCON transition without thorough preparation would cause a catastrophe if a war were to break out. The transition must be pursued with meticulous preparation at four levels: the public, the government, the military, and the alliance.[30]

1) Public and Governmental Level Strategies

The South Korean public must move beyond a mindset of alliance dependence and arm itself with a principle of self-reliant defense and the security values of liberal democracy. History shows that when a nation is divided by internal strife and excessive pacifism, enemies take advantage of the situation without fail. Internal turmoil must never be allowed to invite external crisis. The current political chaos must be stabilized through a politics of integration, coexistence, and cooperation.

The National Security Council (NSC)'s functions must be significantly enhanced, and a national-level war conduct system must be established. This will enable the president to immediately convene and lead the NSC in a severe crisis and effectively implement security policies. We must also build a war conduct system capable of warfighting and victory.[31] Creating a nation capable of warfighting is not only a strategy to prevent war but also a stratagem to win one.

Reserve forces management and wartime mobilization posture must be established. The measures include building systems for mobilizing reserve and civil defense corps members to rapidly fill operational needs for unit expansion or loss replacement when a mobilization order is issued. The monthly civil defense drills must also be conducted with a sense of simulating actual combat situations.

Simultaneously, to create a stable security environment conducive to the transition, inter-Korean political and military dialogues should be pursued, and peace on the peninsula should be managed through ROK-U.S.-China strategic dialogues.

2) Military Level Strategy for OPCON Transition

In a contingency, the ROK military will pursue a strategy to seize air and sea superiority in the early stages of war and neutralize the enemy's strategic center, including its central command. The strategy includes measures to block third-party intervention and seeks to conclude the war by securing key strategic areas and the border through high-speed maneuver warfare, including airborne and amphibious operations.

This requires the early acquisition of intelligence, surveillance, and deep-strike capabilities, and the establishment of a strategic strike system by securing assets including Medium Surface-to-Air Missiles (M-SAM), Long Surface-to-Air Missiles (L-SAM), and counter-firepower capabilities.

Warfighting capabilities, including command and control, intelligence assessment, operational planning, and operational sustainment, must be enhanced. It is urgent to reform the upper-echelon command structure. The dual system of military administration and command must be unified, granting the Chairman of the Joint Chiefs of Staff the authority of a joint forces commander and including the chiefs of staff of each service in the operational chain of command. Only then can the military be reborn as a vital force integrating operations, training, and personnel.

3) Alliance Level Strategy for OPCON Transition

Before the transition, the ROK and U.S. must define the interrelationships among the Joint Chiefs of Staff (JCS), Combined Forces Command (CFC), United Nations Command (UNC), and United States Forces Korea (USFK). The JCS will issue strategic guidance and operational directives to the future CFC through the National Command and Military Authorities and ROK-U.S. consultative bodies. The CFC will develop operational plans, conduct combined exercises, and command peninsular theater operations in a contingency. The UNC will implement the Armistice Agreement and, in a contingency, transfer tactical control of combat units from its member states to the future CFC to fight under a unified command. USFK will maintain combined readiness and, along with U.S. reinforcements, execute its wartime mission under the operational control of the CFC. These roles must be reflected in Strategic Directive No. 3 at the time of the OPCON transition.

A potential command structure for the future CFC could be an ROK General as Commander and the USFK Commander as Deputy Commander.[32] In the staff organization, the Chief of Staff could be a U.S. officer and the Deputy Chief a ROK officer. Considering the importance of ground operations, the Assistant Chief of Staff for Operations (C3) could be a ROK General, while the Assistant Chief of Staff for Plans (C5) could be a U.S. General, given the need for future planning and reinforcement deployment. The Assistant Chief of Staff for Intelligence (C2) could be a ROK General. The ROK Ground Operations Commander could serve as the Combined Ground Component Commander. Considering U.S. reinforcement aviation assets, the Commander of the U.S. 7th Air Force could serve as the Combined Air Component Commander, and the Commander of the U.S. 7th Fleet could serve as the Combined Naval Component Commander. The ROK Special Warfare Commander could lead the Combined Special Operations Component, and the ROK Marine Corps Commandant could lead the Combined Marine Component. The Space Force Commander could be a U.S. officer, and the Cyber Warfare Commander a ROK General.

A Military Coordination Center could be operated within the UNC, headed by the UNC Deputy Commander. It would coordinate the transfer of tactical control of UNC member state combat units to the future CFC and cooperate with international and non-governmental organizations involved in humanitarian assistance.

It is necessary to implement a roadmap for the OPCON transition based on a robust ROK-U.S. alliance, while enhancing the ROK military's surveillance, reconnaissance, operational planning, and command capabilities.[33] The government has determined that completing the second phase of the Full Operational Capability (FOC) assessment in 2025 will be difficult. If the second phase of FOC is passed in 2026, the two sides could discuss a target year for the transition.[34] By setting 2028 as the target year and passing the final, third-phase Full Mission Capability (FMC) assessment in 2027, the evaluation of the future CFC commander's mission capability will be complete. The defense ministers could then recommend the transition to their respective presidents, enabling the transfer of wartime OPCON to the ROK military on January 1, 2028.

5. Responding to the North Korean Nuclear Challenge

North Korea’s nuclear and missile threat is severe. The possibility of an invasion followed by a nuclear surprise attack cannot be ruled out. A comprehensive response is required, including continuously supplementing the ROK's Three-Axis System, implementing integrated extended deterrence, automatically deploying tactical nuclear weapons upon raising the defense readiness posture, and pursuing nuclear balance on the peninsula.[35]

1) Supplementing ROK Three-Axis System

The foremost task is to supplement the Three-Axis System of Kill Chain, Korea Air and Missile Defense (KAMD), and Korea Massive Punishment and Retaliation (KMPR). This involves enhancing its effectiveness and applying a High-Low mix concept to optimize force structure, balancing high-cost, advanced technology assets like ISR and interceptor missiles with conventional forces, including drones. To supplement the system and lower the nuclear threshold, it is imperative to deploy non-lethal weapon systems that could functionally neutralize North Korean weapon systems without causing direct damage, while utilizing cyber, electronic, and psychological capabilities.

For cybersecurity, a Basic Cyber Security Act should be enacted to strengthen integrated response capabilities. The Cyber Operations Command should be upgraded to a Cyber Counterintelligence Command to prevent the leakage of military secrets and advanced technology.[36]

2) Implementing Integrated Extended Deterrence

Second, the alliance should implement the Washington Declaration and integrated extended deterrence. The extended deterrence customized to Korea, agreed upon at the April 26, 2023 summit must be substantively executed. This includes the operation of the Nuclear Consultative Group (NCG), development of execution plans for U.S. nuclear and ROK conventional support, and joint exercises on nuclear deterrence. The government branches of the two states should participate in tabletop simulations for nuclear operations. Strategic assets including strategic nuclear submarines and bombers should be regularly deployed. The ROK's strategic strike system and the ROK-U.S. 4D (Detect, Disrupt, Destroy, Defend) concept must be integrated into the warfighting domain.

Furthermore, the "ROK-U.S. Guidelines for Nuclear Deterrence and Nuclear Operations on the Korean Peninsula" signed on July 11, 2024, must be materialized.[37] The guidelines require the swift progression of the NCG work frame, including security protocols for expanded information sharing, nuclear consultation processes for crises, nuclear strategy and planning, Conventional-Nuclear Integration (CNI), ROK conventional support for U.S. nuclear operations, strategic dialogues, training and simulations, and risk reduction exercises.

3) Automatic Deployment of Tactical Nuclear Weapons upon Raising Defense Readiness Posture

Third, tactical nuclear weapons should be automatically deployed when the ROK-U.S. combined forces raise their defense readiness posture. To maintain strategic stability, tactical nuclear weapons should be rotationally deployed in peacetime or immediately deployed when the Defense Readiness Condition (DEFCON) level is elevated due to heightened tensions. This process requires a bilateral agreement on procedures, storage, and costs of nuclear deterrence, as well as the construction of Weapons Storage and Security Systems (WS3) and training for transportation and mounting.

4) Nuclear Balance on the Peninsula through ROK Nuclear Armament

Fourth, through South Korea’s nuclear armament, the alliance could pursue nuclear balance on the peninsula and promote a new peace and security strategy. Should the Trump administration fail to implement the Washington Declaration or do not redeploy tactical nuclear weapons, South Korea's nuclear armament would be inevitable. The armament would be implemented in four stages: 1) establishing a control tower for nuclear armament and securing nuclear latency; 2) withdrawing from the NPT in an emergency that jeopardizes the country’s supreme interests; 3) pursuing nuclear armament while persuading the U.S. to acquiesce to the program; and 4) after achieving North-South nuclear balance, negotiating nuclear disarmament with North Korea to abolish nuclear weapons and sign a peace treaty.[38] However, South Korea's nuclear armament would be conditional on North-South nuclear reduction or on the premise that all weapons would be dismantled upon unification.

6. Increasing Burden-Sharing and Defense Spending

1) Increasing Defense Burden-Sharing

The two states have agreed on the defense cost-sharing for the five years starting in 2026.[39] South Korea’s contribution in 2026 is set at 1.5192 trillion won, an 8.3% increase from 2025. It is imperative and customary for South Korea to abide by this agreement. Should additional negotiations become unavoidable, the two allies should adhere to the following principles.[40] First, should USFK perform the dual roles of defending Korea and keeping China in check, Seoul’s burden-sharing should be adjusted downward in proportion to its contribution to checking China.

Second, like in Japan, the calculation of South Korea’s defense contribution should include in-kind contributions such as tax relief for USFK on land usage, utilities, and airport and highway tolls, as well as support for KATUSA (Korean Augmentation to the United States Army) soldiers.

Third, it is necessary to highlight that South Korea's contribution to the alliance is clearly higher than that of Japan or Germany.

① South Korea's dispatch of two combat divisions to Vietnam and units to Iraq and Afghanistan is overwhelmingly different from Japan's financial support and limited troop deployment to Iraq or Germany's deployment to Afghanistan.

② South Korea shouldered 91% ($10.9 billion) of the total cost for the Pyeongtaek base relocation ($12 billion).

③ In terms of defense spending as a percentage of GDP (2024 IMF data), South Korea spends 2.7% ($46 billion of $1.65 trillion), far more than Japan's 1.1% ($50.2 billion of $4.39 trillion) and Germany's 1.8% ($86 billion of $4.92 trillion).

④ From 2008-2017, South Korea was the third-largest buyer of U.S. weapons, purchasing $6.73 billion worth, nearly twice Japan’s purchase of $3.75 billion. Such transactions directly contributed to the U.S. economy and job creation.

⑤ South Korea’s defense cost-sharing contribution relative to GDP and the size of stationed U.S. forces is the highest among the three U.S. allies. South Korea contributes $1.1 billion for 28,500 U.S. forces (0.053% of GDP), while Japan spends $1.73 billion for 54,000 U.S. forces (0.034% of GDP), and Germany spends $0.79 billion for 36,000 U.S. forces (0.019% of GDP).

Fourth, in exchange for fair burden sharing, restrictions on South Korea’s defense capacity must be lifted. The measures include technology transfers through joint R&D, redeployment of tactical nuclear weapons and NATO-style nuclear sharing, and revision of the ROK-U.S. Atomic Energy Agreement to allow for reprocessing and uranium enrichment. Also, restrictions on South Korea’s development of nuclear-powered submarines should be lifted to counter the North Korean SLBM threat.

Fifth, negotiations must be fair and reciprocal. A ceiling should be established for any appropriate increase in cost sharing. South Korea could agree to incrementally fund 100% of personnel, construction, and logistics costs, while the U.S. covers the cost of deploying strategic assets and operating USFK equipment. The agreement could include South Korea providing Maintenance, Repair, and Operation (MRO) services for U.S. naval vessels.

2) Increasing the Defense Budget

To counter the advanced North Korean nuclear threat, address unspecified threats from neighboring countries, and prepare for changes in U.S. defense policy and force postures, it is vital for South Korea to build an independent defense capability. A stable defense budget that transcends administrations and party lines is essential. We must recognize that the defense budget is an absolute necessity for national survival and a public good that benefits all citizens. A defense reform for independent defense and enhancement of defense capacity is not a matter of choice.[41]

In the mid-to-long term, it is desirable to incrementally reduce dependence on the U.S. for South Korea's defense. The defense budget must be managed efficiently to secure the necessary financial resources. Noting that there are no eternal alliances in international relations, it is imperative to build a self-reliant defense capacity to fight at any time without external support. We must incrementally replace capabilities dependent on the U.S. and foster a self-sufficient military that could wage war independently.

As of 2025, South Korea's defense budget ($46 billion) is 2.67% of GDP ($1.72 trillion). An estimated 21 trillion won is needed to develop capabilities for the OPCON transition. It is necessary to increase the defense budget in conjunction with the OPCON transition.[42]

III. Conclusion and Policy Proposals

The future vision of the ROK-U.S. alliance at the peninsular, regional, and global levels can be summarized as follows. On the Korean peninsula, the alliance pursues denuclearization of the peninsula and the establishment of a peace regime. In Northeast Asia, the alliance seeks to institutionalize regional security cooperation. Ultimately, the alliance’s goal is to construct a global liberal international order.

To realize this vision, the following policies are proposed:

1. Establish a presidential "ROK-U.S. Korean Unification Consultative Committee" to build a peace regime on the Korean Peninsula. Composed of ROK and U.S. policymakers and experts, the committee would develop a vision and strategy for a unified Korea, enabling the alliance to play a leading role.

2. Establish a "Committee for the Promotion of OPCON Transition" directly under the Commander-in-Chief to pursue the transition as a nationwide effort. This committee would re-examine the conditions, set a target year, manage strategic communication with the public, issue negotiating guidelines, identify necessary actions at all levels, and oversee the entire process, including defense budget increases and command structure reform.

3. Reach an agreement with the U.S. that any redeployment of USFK forces to contingencies outside the peninsula must be accompanied by the simultaneous or prior deployment of backfill assets.

4. Establish a "ROK-U.S.-Japan Trilateral Military Cooperation Task Force," composed of strategic planners from the ROK JCS, U.S. INDOPACOM, and Japan's Joint Staff, to define alliance roles. Through simulations of various war scenarios, it would identify the respective roles and responsibilities of each country.

5. Consult with the U.S. on the automatic deployment of tactical nuclear weapons when the defense readiness posture is elevated. Given the limitations of extended deterrence against a North Korean hypersonic missile attack armed with a nuclear warhead, extraordinary measures are required. The measures involve a bilateral agreement on procedures for use, storage, and costs, and constructing WS3 systems.

By embracing the alliance’s principle of collective defense, completing the wartime OPCON transition, respecting the rationale of USFK's strategic flexibility, and preparing for the immediate deployment of tactical nuclear weapons in a crisis, all while increasing defense spending to fulfill an expanded alliance role, the ROK-U.S. alliance will have the opportunity to evolve into a truly Reciprocal-Symmetric Alliance. ■ 

[1] “美, ‘한미 동맹 현대화’ 협의 공식화… “韓 방위 부담 확대 필요,” 《조선일보》, 2025년 7월 24일.

[2] 전재성, “신정부의 대북전략, 주요변수와 대응전략,” 최종현 학술원-동아시아연구원-서울대 국가미래전략원 공동주최 「글로벌 복합위기, 대한민국의 외교안보 전략 방향」 학술포럼, 2025. 7. 24, 한국고등교육재단컨퍼런스홀.

[3] 이중구, “북한의 ‘적대적 두 국가론’과 남북관계 전망,” 『통일정책연구』, 통권 제33권 1호 (2024).

[4] SIPRI, SIPRI Yearbook 2025 (Stockholm: SIPRI, 2025), p.182.

[5] Bruce W. Bennett, Kang Choi, Myong-Hyun Go, Bruce E. Bechtol, Jr., Jiyoung Park, Bruce Klingner, and Du-Hyeogn Cha, Countering the Risks of North Korean Nuclear Weapons (Santamonica: RAND, April 12, 2021).

[6] BRICS was established in 2002 with Brazil, Russia, India, China, and South Africa as its founding members. Seven countries—Saudi Arabia, Egypt, the United Arab Emirates, Ethiopia, Indonesia, and Iran—later joined in 2024-2025, bringing the total number of member countries to 11.

[7] 반길주, “신냉전 개념을 통해 본 국제질서,” 이관세·반길주·최영준·조성렬·이승주·최용환·전재성, 『신냉전 시대는 도래하는가?』(서울; 경남대학교 극동문제연구소, 2024).

[8] 박동찬, 『통계로 본 6·25전쟁』 (서울: 군사편찬연구소, 2014).

[9] 국방군사연구소, 『한국전쟁 피해통계집』(서울: 국방군사연구소, 1996), p. 135.

[10] 김충환, “부산총회 결과와 국회의 역할,” 『국제개발협력』 2011년 4호 (2011), p. 51.

[11] 정경영, “평화협정 체결과 주한미군의 미래,” EAI Issue Briefing, 2018. 7. 24.

[12] 정경영, 『피스 크리에이션, 한미동맹과 평화창출』(파주: 한울아카데미, 2020), pp. 150-184.

[13] The White House, “Leaders’ Joint Statement in Commemoration of the 70th Anniversary of the Alliance between the United States of America and the Republic of Korea,” April 26, 2023.

[14] Chung Kyung-young, “Building a Military Security Cooperation Regime in Northeast Asia: Feasibility and Design,” PhD Dissertation, University of Maryland (2005), pp. 345-348.

[15] 이승만 기념관, “한미상호방위조약 원문 (1953년 10월 1일)” 건국대통령 업적과 연구자료 제공 (Accessed: 2025. 8. 20).

[16] 최용호, 『베트남전쟁과 한국군』(서울: 보라, 2010).

[17] “‘해상 3축체계 중추’ 해군 기동함대사령부 닻 올렸다,” 《국방일보》, 2025. 2. 3: Established on February 3, 2025, the Jeju Task Fleet Command is responsible for missions such as protecting sea lines of communication, maintaining a readiness posture against North Korea, and deploying the Cheonghae Unit for escort missions in the waters off Somalia. The command operates approximately 10 destroyers, including the 8,200-ton Aegis destroyer ROKS Jeongjo the Great (DDG-II), and the 10,000-ton fast combat support ship ROKS Soyang (AOE-II).

[18] “함께할 때 더 강해져”… 하나된 ‘한미 해병대’ 연합훈련 전개,” 《아시아 투데이》, 2025. 8. 6: The Combined Landing Exercise is a key component of the Korea Marine Exercise Program (KMEP) and is conducted annually by the ROK-U.S. Marine Corps. KMEP is a training program for the U.S. Marine Corps to deploy to the Korean Peninsula to improve the combined operational capabilities and interoperability of the ROK and U.S. Marine Corps. Approximately 1,500 U.S. Marines from the 3rd Marine Division of the III Marine Expeditionary Force, stationed in Okinawa, participate in the exercise. They share combat skills and tactics with their counterparts from the ROK Marine Corps' 1st and 2nd Divisions, 6th Brigade, Yeonpyeong Unit, Marine Aircraft Group, and Marine Logistics Group.

[19] The White House, “The Spirit of Camp David: Joint Statement of Japan, the Republic of Korea, and the United States,”(Aug 18, 2023).

[20] 외교부, 『2024외교백서, 2024년도 국제정세와 외교활동』(서울: 외교부, 2025).

[21] 국정홍보처, “‘전략적 유연성’관련 설명 자료,” 2006. 1. 23.

[22] “한반도 중심에서 인도태평양 다영역 작전 체제로,” 전세계가 한국만 보고 있다 “주한미군의 판도가 180도 뒤바뀌게 된 이유” (Accessed: 2025. 8. 19).

[23] 김정섭, “트럼프 발 3중도전과 능동적 동맹변화,” 최종현 학술원-동아시아연구원-서울대 국가미래전략원 공동주최, 「글로벌 복합위기, 대한민국의 외교안보 전략 방향」” 학술포럼 2025.7.24, 한국고등교육재단빌딩 컨퍼런스홀.

[24] “전작권 전환, 지름길 택하면 한반도 대비 태세 위태로울 수 있다,” 《조선일보》, 2025. 8. 11.

[25] Alex Horton and Hannah Natanson, “Secret Pentagon memo on China, homeland has Heritage fingerprints,” The Washington Post, March 29, 2025.

[26] “국정위, '국정 운영 5개년 계획' 발표 … "임기 내 전작권 전환",” 《뉴데일리》, 2025. 8. 13.

[27] “‘타이완 전쟁’ 시 한국 스스로 방어해야…미국도 한국 판단 존중할 것,” VOA, 2024. 1. 20.

[28] 국방부, “전작권 전환의 3대 조건,”대한민국 정책브리핑(www.korea.kr (Accessed: 2025. 7. 30).

[29] “Resolution of the Department of Defense of the United States of America and the Ministry of National Defense of the Republic of Korea: Guiding Principles Following the Transition of Wartime Operational Control,” https://kr.usembassy.gov/ (Accessed: 2025. 3. 28).

[30] 정경영, 『전작권 전환과 국가안보』(서울: 도서출판 매봉, 2023), pp. 105-129.

[31] 하정열, “대통령의 전쟁지도 개념 검토,” 한국전략문제연구소 정책연구보고서, 2010. 9: The conduct of war refers to the execution of supreme command to deter war in peacetime and achieve victory during a contingency. It signifies the leadership and art of organizing a nation's total capacity by integrating, coordinating, and controlling both national and military strategies.

[32] 정경영, “전작권 전환과 북핵 포괄적 응전전략 및 군구조 개편,” 한국핵안보전략포럼 엮음, 『한국의 핵안보 프로젝트 1 당위성과 추진전략』(서울: 블루앤노트, 2025), pp. 343-375.

[33] “국정기획위, 전작권 전환 “일체형과 병렬형 중 검토 필요,” 《경향신문》, 2025. 8. 13.

[34] “정부, 美 국방비 증액 요구에 ‘전작권 전환’ 연계 방침,” 《동아일보》, 2025년 8. 7.

[35] 정경영, “전작권 전환과 북핵 포괄적 응전전략 및 군구조 개편,”한국핵안보전략포럼 엮음, 『한국의 핵안보 프로젝트 1 당위성과 추진전략』(서울: 블루앤노트, 2025), pp.343-375.

[36] 김희철, “북한 사이버 해커 8100억원 탈취, 우리의 대응책은?,” 한양대 국가전략연구소・안보협업연구소 공동 주최 「최근 북한 ICT 현황과 전망」 학술회의 (2022. 11. 30).

[37] The White House, “Joint Statement by President Joseph R. Biden of the United States of America and President Yoon Suk-yeol of the Republic of Korea on US-ROK Guidelines for Nuclear Deterrence and Nuclear Operations on the Korean Peninsula,” (July 11, 2024).

[38] 정성장, 『왜 우리는 핵보유국이 되어야 하는가: 패권경쟁 시대, 전쟁을 막을 최선의 안보 전략』 (서울: 메디치미디어, 2023), pp.119-139.

[39] “2026년 주한 미군 한국 분담금, 내년보다 8.3% 늘어 1.5조원,” 《조선일보》, 2024. 10. 5.

[40] 정경영, 『피스 크리에이션, 한미동맹과 평화창출』(파주: 한울아카데미, 2020), pp.184-191.

[41] 전제국, “국방비 소요 전망과 확보 대책,” 『새 정부의 국방정책 방향』(서울: 한국전략문제연구소, 2017. 7. 15), p.138.

[42] “정부, 美 국방비 증액 요구에 ‘전작권 전환’ 연계 방침,” 《동아일보》, 2025. 8. 7.

■ Kyung-young CHUNG is an Adjunct Professor at the Hanyang University Graduate School of International Studies.

■ Translated and Edited by Inhwan OH, Senior Research Fellow; Jonghyuk CHUNG, Researcher, Korea National Diplomatic Academy
    For inquiries: 02 2277 1683 (ext. 202) | ihoh@eai.or.kr