[Global NK Commentary] Modernizing the ROK-US Alliance: Wartime OPCON Transfer and Inter-Korean Relations Transformation

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President Trump's foreign and security policy is shaking the foundation of existing US alliance policy. Trump is a MAGA president, elected twice with the slogan "Make America Great Again (MAGA)." His method is "America First." American Firstism manifests as a rejection of the UN and multilateralism in the international order. In alliance policy, it appears as a shift from reciprocal relationships to burden-sharing through tariffs and increased US troop presence costs, and a strategy of each nation for itself. In this process, all relationships, including alliances, are defined as bilateral transactions led by Trump. The winner in a deal with Trump is already decided: Trump and the United States must gain more.

In 2019, the Trump administration pressured NATO members, including Germany, to increase their defense spending to 2% of GDP. When Germany responded lukewarmly, Trump threatened to withdraw US troops stationed in Germany and relocate them to Poland. Two years after the outbreak of the Ukraine war, in 2024, President Trump's pressure has intensified. European leaders, concerned about the US withdrawing from NATO, agreed at the NATO summit in June 2025 to increase defense spending to 5% of GDP by 2035. President Trump is also continuously pressuring South Korea and Japan to increase defense cost-sharing, boost defense spending, and procure US weapons. Amidst this, US media reported in May that the US Department of Defense was preparing a plan to relocate approximately 4,500 of the roughly 28,500 US troops stationed in South Korea to other regions in the Indo-Pacific.

The ROK-US summit held on August 25, 2025, was a focal point of intense interest regarding what security demands Trump would present. President Trump mentioned increased arms purchases by South Korea, stating, "South Korea is a major buyer of our military equipment." When asked by a reporter about a 'plan to reduce USFK,' he proposed transferring land ownership of US military bases to the United States instead of a reduction. This appears to be a misunderstanding of the current situation in South Korea, where US military sites are provided free of charge, unlike the lease-based arrangements in Germany and Japan. Regardless, Trump's desire to own the land for USFK could be interpreted as revealing the US's underlying intention not to easily leave South Korea.

Although there was no controversy over defense cost-sharing at this summit, the truly important issue of USFK has become the 'modernization of the ROK-US alliance' raised before and after President Lee's visit to the US. In this regard, the strategic flexibility of USFK is emerging as a key issue. It is known that Assistant Secretary of Defense for Policy under the second Trump administration, Elbridge Colby, has a plan to have South Korea responsible for deterrence against North Korea and defense of the Korean Peninsula, while USFK would be utilized for containment of China. This appears to be a convergence of Trump's desire for burden-sharing from allies and the US Department of Defense's strategy of containing China. In this scenario, the primary mission of USFK could shift from 'deterrence against North Korea' to 'managing areas near the Korean Peninsula, including Taiwan.' This is a significant issue that could expand the mission of the ROK-US alliance from North Korean deterrence to Chinese deterrence, entail increased defense cost-sharing by South Korea, the transfer of wartime operational control, and strengthened linkage with US Forces Japan.

The current administration is actively pursuing the transfer of wartime operational control as a long-term solution to these complex issues. Discussions on the transfer of wartime OPCON began during the Roh Tae-woo administration and were pursued in earnest after the Roh Moo-hyun administration. In the interim, due to the advancement of North Korea's nuclear program and changes in the Korean Peninsula situation, it has remained an unfinished task, oscillating between conservative and progressive governments. The conditions for the South Korean military to independently conduct operations and the security environment have not yet been met. However, in the current rapidly changing ROK-US alliance and the geopolitical landscape of Northeast Asia, it has become a task that can no longer be postponed.

The reasons are as follows. First, the expansion of South Korea's defense responsibilities due to its rapid economic growth has become a task of the ROK-US alliance for this era. The US government's demands for an expanded role for the South Korean military have been steadily increasing. The ultimatum from the Trump administration is a matter of time. Second, it appears natural to third parties that South Korea, recognized as the world's fifth-largest military power, should be responsible for its own defense. Third, South Korea's increased defense spending for OPCON transfer is the most effective means to respond to President Trump's demand for increased defense budgets. The cost for OPCON transfer serves the dual purpose of demonstrating sincerity in response to the US demand for up to double the current budget, while also being an essential long-term investment for South Korea. Fourth, the issue of strategic flexibility of USFK can be supplemented in the mid- to long-term through OPCON transfer. A reduced security dependence on the US will strengthen our negotiating power in security talks with China and the US. We can minimize the role of USFK concerning China or present South Korea's independent security policy to China.

President Trump's foreign policy is shaking the foundations of the international order established under US leadership over the past 80 years. The US, once a proponent of democracy and free trade, is now threatening the world by prioritizing hegemony and protectionism. South Korea, which has achieved remarkable economic growth and democratization based on the ROK-US alliance and world trade, must now deal with a very different America. The US, boasting the world's leading military, economic, and technological capabilities, remains the most important partner. At the same time, we must adapt to the changing face of America and South Korea's evolving role. The recent ROK-US summit could be a turning point for 21st-century ROK-US relations, going beyond just the first meeting between the two presidents. President Lee Jae-myung stated at a gathering of Korean-Americans residing in the US, "We are embarking on an important journey to open a new path for the 72-year-old ROK-US alliance." President Lee proposed that "the ROK-US relationship, which began as a military alliance, is now evolving into a future-oriented comprehensive strategic alliance encompassing economic and technological alliances."

The starting point is the recognition of South Korea's new status and role. As a leading advanced technology economy, second only to the US and China, and possessing the world's fifth-largest military, South Korea can no longer rely solely on the goodwill of the United States. We must also recognize the reality of South Korea's growing role in the US-China strategic competition of the 21st century. The Korean Peninsula's strategic location is crucial for the US's Indo-Pacific military strategy. South Korea's semiconductor production is an indispensable element in the US-China AI competition. South Korea's nuclear power plant construction and small modular reactor technology are also capabilities needed by the US in securing energy sources, another pillar of the AI competition. Large-scale investments by South Korean companies in manufacturing sectors such as automobiles, batteries, chemicals, and aerospace are important for job creation and the development of next-generation industries in the US. President Trump and the US, who have sought assistance from the South Korean shipbuilding industry, are well aware of this reality.

The Trump administration's demand for alliance modernization has presented South Korea with the challenges of preventing a deterrence gap against North Korea, securing defense sovereignty, and maintaining diplomatic balance amidst US-China competition. In the short term, the scope and conditions of strategic flexibility need to be negotiated, and in the mid- to long-term, the enhancement of advanced military capabilities and the expansion of multilateral security cooperation are required. The transfer of wartime operational control will be a turning point in the modernization of the ROK-US alliance in the 21st century. Since the Korean War, South Korea took a significant step towards self-reliant defense by transferring peacetime operational control in the 1990s. Since then, South Korea's conventional forces have reached a level where they can independently produce and export world-class tanks, self-propelled artillery, warships, submarines, and fighter jets. However, surveillance, reconnaissance, and intelligence capabilities, which are the eyes and ears of warfare, are still dependent on the United States. The increase in South Korea's defense budget, driven by Trump's pressure, should be directed towards strengthening precision strike capabilities, C4ISR intelligence assets, cyber, and missile defense capabilities. The transfer of wartime operational control will complement these capabilities, marking the final step towards genuine self-reliant defense.

The transfer of wartime OPCON can also be a significant turning point for long-term inter-Korean relations and North Korea negotiations. Traditionally, North Korea has pursued a policy of engaging with the US while excluding South Korea in Korean Peninsula security matters, referring to the South Korean military as a US proxy (Tongmi Bongnam). In a recent speech at the Supreme People's Assembly, North Korean leader Kim Jong-un declared "denuclearization is impossible" and reiterated the severance of inter-Korean relations. Kim Jong-un's speech is intended to solidify North Korea's status as a nuclear-weapon state in the international community and to preempt the denuclearization demands from South Korea and the US. It also appears to signal an intention to permanently entrench the division of the Korean Peninsula into two systems, moving beyond mere rhetoric of North and South being 'hostile states.'

The transfer of wartime OPCON will prevent North Korea from disregarding South Korea's military sovereignty any longer. This is because South Korea, as a military power that will lead military operations on the Korean Peninsula, will confront North Korea on major security issues such as nuclear weapons and arms control. In his speech on Armed Forces Day, President Lee Jae-myung stated that self-reliant defense is inevitable to actively respond to the rapidly changing security environment. He declared that South Korea must move towards strong self-reliant defense as a military power with a defense budget 1.4 times that of North Korea's GDP and the world's fifth-largest military. Furthermore, he pledged to restore wartime operational control based on a firm ROK-US alliance, enabling the Republic of Korea to lead the combined defense posture.

The stable management of the Korean Peninsula situation and the maintenance of peace are South Korea's most important security and national interests. President Lee declared that the ROK-US alliance is the cornerstone of South Korean diplomacy. However, diplomacy that solely looks to the United States is no longer effective. Former Singaporean Prime Minister Lee Kuan Yew argued that even in a "World Minus One" scenario where the US disappears from the global trade order, other countries will still have to trade based on free trade and comparative advantage. In the security order as well, we can no longer expect unilateral assistance from the United States. We look forward to the modernization of the ROK-US alliance, which will further strengthen the two pillars of the ROK-US alliance and self-reliant defense. ■

■ Shin Sung-ho_Professor, Graduate School of International Studies, Seoul National University.

■ Responsible Editor: Lee Sang-jun_EAI Research Fellow

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