Asia Defense | Security | East Asia

Modernizing the South Korea-US Alliance Requires Checking the Assumptions

Both Seoul and Washington want to “modernize” the alliance – but they have different goals in mind.

Republic of Korea soldiers construct a bridge with a group of U.S. soldiers during combined wet gap crossing training as part of Ulchi Freedom Shield near Yeoju, South Korea, Aug 27, 2025.

The United States” “Operation Epic Fury” in Iran is a prime example of the inter-connectedness of modern international affairs. A crisis in the Middle East is now inextricably linked to the Indo-Pacific. While President Donald Trump has repeatedly argued the U.S. munitions and materiel are virtually infinite, sources claim that the United States is close to exhausting its air defense capabilities in the Middle East. 

Against that backdrop, the air defense batteries – particularly the Patriot launchers – belonging to the United States Forces Korea (USFK) gathered at Osan Air Base on March 5 local time. There’s speculation that this may signal their potential redeployment to Iran.

This news fueled a heated debate in the Korean National Assembly over whether the combined defense readiness posture on the Korean Peninsula could be weakened by the transfer of U.S. capabilities among different U.S. forces. The opposition People Power Party harangued the government’s silence on the topic as “excessively complacent and vague.”

The transfer revived an unwelcome debate over a potential “fissure” in the South Korea-U.S. alliance and the readiness posture on the Korean Peninsula. The rare February 19 aerial standoff between the USFK and Chinese fighter jets, as well as the disputes surrounding the extent of the Korea-U.S. Field Training Exercises (FTX) as part of the upcoming Freedom Shield Combined Command Post Exercise (CPX), sparked national interest in the integrity of the alliance. The question is whether these disagreements are occasional and administrative in nature, or a true preview of a faltering alliance. 

The aerial standoff issue was more or less resolved following USFK Commander General Xavier Brunson’s expression of regret over the delayed notification – despite USFK’s adherence to the proper “alliance” timeline – for the West Sea aerial exercise to South Korea’s Ministry of National Defense and the Joint Chiefs of Staff. The new issue surrounding the extent of the FTXs is equally unusual. CPXs, which orchestrate strategic-level decision-making for the alliance, and FTXs, which execute tactical-level training with real soldiers and equipment, usually require the submission of various logistical requirements months before the exercise. As per the combined exercise plan, continental U.S. (CONUS) augmentees and equipment had already arrived before Seoul’s demand for lower-key, reduced FTXs.

Seoul’s unilateral move to reduce the extent of the FTXs cannot be interpreted without considering the February 6 easing of U.N. sanctions against North Korea, which would allow humanitarian aid to reach the country – a move interpreted as “a push by Seoul and Washington to engage Pyongyang.” Seoul appears to suggest that Washington’s willingness to engage North Korea – perhaps during Trump’s state visit to China from March 31-April 2 – supersedes military-to-military priorities.

Connecting the dots, however, reveals a slightly different interpretation of these pending issues: they represent subtle politico-military maneuvers by Seoul and Washington not only to maximize their respective national interests, but also to signal their own preview of “alliance modernization,” with each side interpreting the concept through slightly different assumptions.

For the USFK, alliance modernization may mean greater latitude for strategic maneuvering – perhaps best illustrated by the current redeployment of Patriot batteries elsewhere, most likely to Iran. This will allow USFK to keep China’s People’s Liberation Army (PLA) in check, ideally never moving beyond the First Island Chain. Even within the current alliance architecture that prioritizes the defense of the Korean Peninsula, the triple-hatted USFK commander – concurrently the commander of Combined Forces Command and the United Nations Command – can order USFK-only elements to carry out unilateral operations and asset transfers if deemed necessary to defend the peninsula, directly or indirectly. Such orders need not be bound by combined-level agreements formed between the Korean and U.S. presidents. Going forward – though likely subject to further interpretation and debate within Seoul – USFK-only operations may increase in number as Washington seeks to execute its broader strategy of keeping the Indo-Pacific open and rules-based.

For Seoul, modernization means greater freedom to pursue inter-Korean dialogue without the political constraints posed by the aforementioned CPXs, which Pyongyang has always regarded as offensive in nature. If alliance-level CPXs and FTXs are seen as hamstringing the Blue House’s diplomatic maneuvering, Seoul would not hesitate to curb or spread them out, avoiding sensitive dates such as April 15, Kim Il Sung’s birthday, for instance. 

Unlike the previous Yoon administration, Seoul’s confidence lies in Trump’s willingness to once again engage Pyongyang, potentially opening the door for renewed inter-Korean and North Korea-U.S. dialogue that could eventually expand into various forms of economic cooperation. In this view, CPXs are part of Seoul’s broader inter-Korean strategy rather than an independent military exercise.

Korean media reports use rather sensitive words, such as “rife” and “rupture,” to describe the current tug-of-war between USFK and Seoul. Yet the South Korea-U.S. alliance has experienced far worse in the past. In the 1970s, then-presidents Jimmy Carter and Park Chung-hee exchanged heated rhetoric that raised the possibility of a complete USFK withdrawal from the Korean Peninsula. The alliance in the early 2000s witnessed another tempest, when then-South Korean President Roh Moo-hyun opposed U.S. plans to make its forces more maneuverable and lighter for overseas deployment, a move that caused uproar in Washington. 

Compared with these earlier episodes, the current situation – tense as it may be – does not warrant a dismal prediction of the alliance’s future. The alliance will likely prevail once again because, despite appearances, the differing views held by each side can be reconciled: keeping China in check while pursuing inter-Korean dialogue and cooperation can be – and indeed should be – compatible objectives for Seoul.

For instance, many argue that restoring the September 19 Comprehensive Military Agreement (CMA) with Pyongyang as Seoul’s next agenda item would invite further disputes and drive wedges within the alliance. Despite the media’s concerned tone, however, restoring the CMA would affect the combined readiness posture only to a minimal extent. Even without near-border intelligence, surveillance, and reconnaissance (ISR) activities conducted by Korean Army division- and battalion-level drones, the high-altitude ISR patrol aircraft of USFK can sufficiently carry out missions to keep the readiness posture intact.

Interestingly, the supposed ISR gap posed by the CMA can be – and has already been – mitigated by the Korean military. Since 2023, Seoul’s continued efforts to launch ISR satellites now allow surveillance of North Korean territory roughly every two hours, a substantial improvement from the pre-2023 period, when South Korea had none and relied entirely on U.S. surveillance satellites that provided coverage only twice a day. 

In this sense, the Korean military could view the reintroduction of the CMA as another opportunity to bridge remaining gaps, particularly through the deployment of high-altitude drone ISR capabilities operating 10 to 20 km from the Demilitarized Zone. Further development and integration of such multi-layered ISR assets would enable the alliance to share a more complete Common Operational Picture (COP) of the Korean theater, while also providing high-resolution, lattice-like monitoring capabilities in the event of third-party intervention – such as from China.

Both sides face hurdles. For Seoul, a critical question remains: how to achieve the Conditions-based Operational Control Transition Plan (COTP) without – or with a reduced level of – the already agreed-upon verification mechanisms in key military sectors, namely the aforementioned ISR assets, as well as the execution of watertight alliance-level CPXs and FTXs, which serve as testbeds for such operational verification. If Seoul cannot manage disputes surrounding substantial – though not complete – transfers of USFK assets, such as the current Patriot battery issue, the persuasiveness and credibility of the administration’s ability to address North Korea’s conventional threats, as Undersecretary of Defense Elbridge Colby often puts it, will ring hollow. 

For USFK, engaging the PLA near the Korean Peninsula without relying on combined-level assets, and in the absence of Seoul’s explicit support, presents a strategic conundrum. 

Ultimately, the path for the alliance to prevail once again lies in locktight consultation, trust in the mechanisms already built, and a clear understanding of each side’s assumptions about what “alliance modernization” truly means.

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The United States” “Operation Epic Fury” in Iran is a prime example of the inter-connectedness of modern international affairs. A crisis in the Middle East is now inextricably linked to the Indo-Pacific. While President Donald Trump has repeatedly argued the U.S. munitions and materiel are virtually infinite, sources claim that the United States is close to exhausting its air defense capabilities in the Middle East. 

Against that backdrop, the air defense batteries – particularly the Patriot launchers – belonging to the United States Forces Korea (USFK) gathered at Osan Air Base on March 5 local time. There’s speculation that this may signal their potential redeployment to Iran.

This news fueled a heated debate in the Korean National Assembly over whether the combined defense readiness posture on the Korean Peninsula could be weakened by the transfer of U.S. capabilities among different U.S. forces. The opposition People Power Party harangued the government’s silence on the topic as “excessively complacent and vague.”

The transfer revived an unwelcome debate over a potential “fissure” in the South Korea-U.S. alliance and the readiness posture on the Korean Peninsula. The rare February 19 aerial standoff between the USFK and Chinese fighter jets, as well as the disputes surrounding the extent of the Korea-U.S. Field Training Exercises (FTX) as part of the upcoming Freedom Shield Combined Command Post Exercise (CPX), sparked national interest in the integrity of the alliance. The question is whether these disagreements are occasional and administrative in nature, or a true preview of a faltering alliance. 

The aerial standoff issue was more or less resolved following USFK Commander General Xavier Brunson’s expression of regret over the delayed notification – despite USFK’s adherence to the proper “alliance” timeline – for the West Sea aerial exercise to South Korea’s Ministry of National Defense and the Joint Chiefs of Staff. The new issue surrounding the extent of the FTXs is equally unusual. CPXs, which orchestrate strategic-level decision-making for the alliance, and FTXs, which execute tactical-level training with real soldiers and equipment, usually require the submission of various logistical requirements months before the exercise. As per the combined exercise plan, continental U.S. (CONUS) augmentees and equipment had already arrived before Seoul’s demand for lower-key, reduced FTXs.

Seoul’s unilateral move to reduce the extent of the FTXs cannot be interpreted without considering the February 6 easing of U.N. sanctions against North Korea, which would allow humanitarian aid to reach the country – a move interpreted as “a push by Seoul and Washington to engage Pyongyang.” Seoul appears to suggest that Washington’s willingness to engage North Korea – perhaps during Trump’s state visit to China from March 31-April 2 – supersedes military-to-military priorities.

Connecting the dots, however, reveals a slightly different interpretation of these pending issues: they represent subtle politico-military maneuvers by Seoul and Washington not only to maximize their respective national interests, but also to signal their own preview of “alliance modernization,” with each side interpreting the concept through slightly different assumptions.

For the USFK, alliance modernization may mean greater latitude for strategic maneuvering – perhaps best illustrated by the current redeployment of Patriot batteries elsewhere, most likely to Iran. This will allow USFK to keep China’s People’s Liberation Army (PLA) in check, ideally never moving beyond the First Island Chain. Even within the current alliance architecture that prioritizes the defense of the Korean Peninsula, the triple-hatted USFK commander – concurrently the commander of Combined Forces Command and the United Nations Command – can order USFK-only elements to carry out unilateral operations and asset transfers if deemed necessary to defend the peninsula, directly or indirectly. Such orders need not be bound by combined-level agreements formed between the Korean and U.S. presidents. Going forward – though likely subject to further interpretation and debate within Seoul – USFK-only operations may increase in number as Washington seeks to execute its broader strategy of keeping the Indo-Pacific open and rules-based.

For Seoul, modernization means greater freedom to pursue inter-Korean dialogue without the political constraints posed by the aforementioned CPXs, which Pyongyang has always regarded as offensive in nature. If alliance-level CPXs and FTXs are seen as hamstringing the Blue House’s diplomatic maneuvering, Seoul would not hesitate to curb or spread them out, avoiding sensitive dates such as April 15, Kim Il Sung’s birthday, for instance. 

Unlike the previous Yoon administration, Seoul’s confidence lies in Trump’s willingness to once again engage Pyongyang, potentially opening the door for renewed inter-Korean and North Korea-U.S. dialogue that could eventually expand into various forms of economic cooperation. In this view, CPXs are part of Seoul’s broader inter-Korean strategy rather than an independent military exercise.

Korean media reports use rather sensitive words, such as “rife” and “rupture,” to describe the current tug-of-war between USFK and Seoul. Yet the South Korea-U.S. alliance has experienced far worse in the past. In the 1970s, then-presidents Jimmy Carter and Park Chung-hee exchanged heated rhetoric that raised the possibility of a complete USFK withdrawal from the Korean Peninsula. The alliance in the early 2000s witnessed another tempest, when then-South Korean President Roh Moo-hyun opposed U.S. plans to make its forces more maneuverable and lighter for overseas deployment, a move that caused uproar in Washington. 

Compared with these earlier episodes, the current situation – tense as it may be – does not warrant a dismal prediction of the alliance’s future. The alliance will likely prevail once again because, despite appearances, the differing views held by each side can be reconciled: keeping China in check while pursuing inter-Korean dialogue and cooperation can be – and indeed should be – compatible objectives for Seoul.

For instance, many argue that restoring the September 19 Comprehensive Military Agreement (CMA) with Pyongyang as Seoul’s next agenda item would invite further disputes and drive wedges within the alliance. Despite the media’s concerned tone, however, restoring the CMA would affect the combined readiness posture only to a minimal extent. Even without near-border intelligence, surveillance, and reconnaissance (ISR) activities conducted by Korean Army division- and battalion-level drones, the high-altitude ISR patrol aircraft of USFK can sufficiently carry out missions to keep the readiness posture intact.

Interestingly, the supposed ISR gap posed by the CMA can be – and has already been – mitigated by the Korean military. Since 2023, Seoul’s continued efforts to launch ISR satellites now allow surveillance of North Korean territory roughly every two hours, a substantial improvement from the pre-2023 period, when South Korea had none and relied entirely on U.S. surveillance satellites that provided coverage only twice a day. 

In this sense, the Korean military could view the reintroduction of the CMA as another opportunity to bridge remaining gaps, particularly through the deployment of high-altitude drone ISR capabilities operating 10 to 20 km from the Demilitarized Zone. Further development and integration of such multi-layered ISR assets would enable the alliance to share a more complete Common Operational Picture (COP) of the Korean theater, while also providing high-resolution, lattice-like monitoring capabilities in the event of third-party intervention – such as from China.

Both sides face hurdles. For Seoul, a critical question remains: how to achieve the Conditions-based Operational Control Transition Plan (COTP) without – or with a reduced level of – the already agreed-upon verification mechanisms in key military sectors, namely the aforementioned ISR assets, as well as the execution of watertight alliance-level CPXs and FTXs, which serve as testbeds for such operational verification. If Seoul cannot manage disputes surrounding substantial – though not complete – transfers of USFK assets, such as the current Patriot battery issue, the persuasiveness and credibility of the administration’s ability to address North Korea’s conventional threats, as Undersecretary of Defense Elbridge Colby often puts it, will ring hollow. 

For USFK, engaging the PLA near the Korean Peninsula without relying on combined-level assets, and in the absence of Seoul’s explicit support, presents a strategic conundrum. 

Ultimately, the path for the alliance to prevail once again lies in locktight consultation, trust in the mechanisms already built, and a clear understanding of each side’s assumptions about what “alliance modernization” truly means.

James JB Park, a captain (S/R) of the Republic of Korea Army, is a senior fellow at the Indo-Pacific Studies Center, of the Pacific Forum, at the University of Vienna’'s European Center for North Korean Studies, and at the West Point Modern Warfare Institute’s Irregular Warfare Initiative. Captain Park also holds rising scholar positions in the Atlantic Council’s KOR-US-AUS trilateral initiative, the Pacific Forum, and the Royal United Service Institute.

alliance modernization

Conditions Based OPCON Transition Plan (COTP)

Inter-Korean relations

U.S. troops in South Korea

U.S.-South Korea alliance

U.S.-South Korea military exercises

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