[Global NK Commentary] Challenges Imposed on the ROK-U.S. Alliance: Alliance Transformation for U.S. Containment of China under the Trump Administration

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Six months into the presidency of Donald J. Trump, the world is witnessing unprecedented changes. Notably, Trump is aggressively pressuring allies and friendly nations in the two major domains of economy and security, represented by tariffs and defense cost-sharing. This article analyzes the foreign and alliance policies of the Trump administration and their potential impact on the ROK-U.S. alliance.

Trump Administration's Foreign Policy Stance

1) Linking Economy and Security

The core of the Trump administration's second-term foreign policy is to prioritize containing China, which leads to demands for increased responsibility and cost-sharing from allies and friendly nations by linking security and economy. Steve Myron, current Chairman of the White House Council of Economic Advisers, diagnoses that the U.S. has provided economic and security public goods as a "benevolent hegemon," but this has imposed excessive costs on the U.S. The financial burden, in particular, has become prominent, with continuous currency distortions arising from the U.S. dollar's role as the global reserve currency. He criticizes some countries for intentionally devaluing their currencies to maintain a strong dollar and thus secure trade competitiveness. As a solution, he argues that the U.S. must no longer tolerate "free-riding" by countries that have benefited from U.S. security and economic public goods. He calls for the U.S. to manage exchange rates and utilize tariffs to revive U.S. manufacturing.[1]

In this process, the emphasis is placed on burden-sharing by allies and friendly nations, linking security and economy. For the U.S. to continue providing economic and security public goods as a "hegemon," improvements in international burden-sharing are necessary. If other countries wish to benefit from the U.S. security and financial umbrella, they must share the responsibility to reduce the burden on the American people.[2] U.S. Secretary of the Treasury Scott Bessent echoed this sentiment, stating that "tariffs should be used as a tool of foreign policy and national security."[3] Specifically, he argues for classifying countries into "green (friendly), yellow (neutral), and red (competitor)" groups based on their monetary policies, trade agreements, security arrangements, and values. Different tariff rates would apply to each group, and conditions and pathways for countries to move to higher groups should be provided.[4]

It is also emphasized that allies and friendly nations should be compelled to participate in China containment by combining tariff barriers with security commitments. Myron states, "From the U.S. perspective, it is not a loss for other countries to maintain their current China policy and choose to accept high U.S. tariffs. Within this system, paying high tariffs provides revenue to the U.S. and simultaneously reduces the U.S. security burden."[5] In other words, it is a warning that if allies do not increase their security burden-sharing to contain China, they will face high tariffs and a reduction or withdrawal of U.S. defense commitments.

2) China Containment

The U.S. officially began prioritizing a response to the China threat during the Barack Obama administration. Subsequently, both the 2018 and 2022 National Defense Strategies, published during the first Trump and Biden administrations, respectively, identified the People's Republic of China as the most significant challenge to the U.S. Department of Defense.[6]

Following the first Trump administration, the second administration emphasizes a response by highlighting the China threat to the maximum extent. The U.S. Department of Defense's "Interim National Defense Strategy Guidance," reported by U.S. media in late March, posits China's threat as the "only pacing threat."[7] A pacing threat refers to the core threat that the U.S. Department of Defense uses as a basis for planning and executing military strategy, force structure, weapons development, budget allocation, and training. The guidance denies the fait accompli of Taiwan's occupation and declares that defending the U.S. homeland is the Department of Defense's sole pacing scenario. The difference from previous strategies is that while both the first Trump administration and the Biden administration designated China as the U.S.'s greatest threat and prepared forces for conflict in the Indo-Pacific, this guidance considers the Taiwan invasion scenario as the sole and highest priority, readjusting the "entire U.S. military" to the Indo-Pacific region. Accordingly, the guidance plans for war with China only in terms of force structure and resource planning, clearly stating the position of leaving the threat from Moscow to European allies.[8]

Transformation of the ROK-U.S. Alliance

As the Trump administration links economy and security and prioritizes China containment, the alliance is also being adjusted accordingly. First, Trump clearly demands the roles, responsibilities, and cost-sharing of allies and friendly nations. The "Interim National Defense Strategy Guidance" in March stated, "Given U.S. personnel and resource limitations, we will take risks in other theaters, and allies in Europe, the Middle East, and East Asia will be pressured to bear greater responsibility for deterring threats from Russia, North Korea, and Iran."[9] In his 2021 book, Under Secretary of Defense for Policy Elbridge Colby wrote, "The U.S. cannot deter China alone, so Asian allies must strengthen their own defense capabilities and enhance cooperation with the U.S."[10] At the Shangri-La Dialogue in late May, U.S. Secretary of Defense Hagerty made two key demands to allies and friendly nations in the Indo-Pacific region. First, a significant increase in responsibility and cost-sharing.[11] Hagerty sharply criticized that it is "absurd" for Asian countries, exposed to the North Korean threat and a stronger China threat, to spend less when European NATO countries are promising to spend 5% of their Gross Domestic Product (GDP). This can be interpreted as meaning that even South Korea's defense spending of 2.3% of GDP in 2025, exposed to the front lines of the North Korean threat, is insufficient. Second, he made it clear that the strategy of relying on the U.S. for security and China for economy (Anmi-Gyeongjung) is unacceptable. Hagerty argued, "Economic dependence on China not only deepens their malicious influence but also complicates our (U.S.) defense decision-making space when tensions escalate." As mentioned earlier, it was reaffirmed that allies can be pressured through tariffs to increase defense burden-sharing and responsibilities to contain China. In other words, allies are being asked to participate in both security and economic domains to contain China.

The U.S.'s alliance transformation described above can be projected onto the ROK-U.S. alliance in the following ways. First, the "Koreanization" of Korean Peninsula defense. It cannot be ruled out that the primary responsibility for responding to North Korea's conventional threats will be shifted to South Korea, while the U.S. will provide extended deterrence against North Korean nuclear threats. This is because the U.S., aiming to focus on the Indo-Pacific region and ultimately China, seeks to reduce its burden of responding to North Korea's conventional threats. This is also a measure to address the "Lipman Gap" pointed out by Colby during his Senate confirmation hearing in March. The Lipman Gap refers to the imbalance between a nation's foreign and military objectives and the resources (military power, economic strength, political will) available to support them.[12] Colby projected this onto the current U.S. situation, arguing, "On the one hand, there is a serious mismatch between what we (the U.S.) seek to achieve in the world and, on the other hand, the resources and political will to achieve those goals."[13]Currently, the U.S. faces multi-dimensional conflicts but is not adequately prepared, thus demanding that allies bear responsibility for their own defense. Therefore, attempts to significantly reduce the responsibility for South Korean defense cannot be ruled out.

Second, the early transfer of wartime operational control (OPCON) may be pursued. This is an option for the U.S. to reduce its defense responsibilities and burden for South Korea by transferring OPCON early, thereby maximizing the strategic flexibility of U.S. Forces Korea (USFK) for China containment. Colby has also expressed his desire for the transfer of OPCON to South Korea on several occasions. In response to a question about OPCON transfer during his Senate confirmation hearing, he stated, "I believe President Trump's vision for foreign policy includes empowering capable and willing allies like South Korea, and therefore I support efforts to strengthen South Korea's role within the alliance."[14] In his book, he more explicitly wrote, "I support the transfer of OPCON to expand South Korea's defense responsibilities as an ally of the United States."[15] Since the Lee Jae-myung administration in South Korea also included OPCON transfer as one of its presidential campaign pledges, the possibility of both South Korea and the U.S. pursuing it early has increased. The key ultimately lies in realizing the large-scale projection of U.S. forces in the event of a Korean Peninsula contingency. According to existing ROK-U.S. combined operational plans, large-scale reinforcements, including U.S. ground forces, are anticipated in the event of war on the Korean Peninsula. However, the U.S. has been conducting wars primarily with air and naval forces, striking deep into enemy territory while minimizing ground operations. Therefore, the actual strategy that would be mobilized in a Korean Peninsula contingency is limited. The U.S. may reorganize the Combined Forces Command system and transfer OPCON to enable South Korea to function as the primary entity in conducting operations during a contingency on the Korean Peninsula.

Third, the role, scope, and size of USFK may be adjusted. Its operational scope could be expanded from deterring North Korean threats to the broader Indo-Pacific region targeting China. In the event of a conflict in the Indo-Pacific region, the U.S. would seek to utilize its forward-deployed forces in the region in an integrated manner. For example, in the event of a Taiwan Strait crisis, available and useful forces from both USFK and U.S. Forces Japan would be mobilized. This means that USFK would no longer be limited to deterring North Korean threats, and while current forces may not be suitable for projection outside the Korean Peninsula, there is a possibility of reorganization in this direction. Recently, the commander of USFK, Gen. Paul LaCamera, stated, "The role of U.S. Forces Korea is not solely focused on repelling North Korea."[16]"To maintain peace through strength, we must sometimes move to other regions,"[17] he declared, underscoring the expanded role of USFK. Previous commanders had limited the role of USFK solely to the North Korean threat.

Fourth, the Trump administration may provide extended deterrence to South Korea, but this could be linked to cost issues. The "Interim National Defense Strategy Guidance" stated the principle of providing nuclear deterrence: "The U.S. will provide nuclear deterrence against Russia, but NATO will not be able to use forces necessary for homeland defense or China containment."[18] Colby also responded to a question during his confirmation hearing about whether the U.S. would provide extended deterrence by stating, "I believe the ROK-U.S. alliance is very important, and I recognize that we face a serious threat from North Korea... Therefore, the strategic deterrence and defense posture of both the ROK and the U.S. must be reliable and strong."[19]

However, uncertainty remains, as Trump has shown personal interest since his first term in demanding costs associated with the deployment of strategic assets and combined exercises essential for extended deterrence. Notably, starting with the press conference following the U.S.-North Korea Singapore agreement in June 2018,[20] Trump has publicly expressed his perception of ROK-U.S. combined exercises as "expensive," "provocative," and "war games," and may demand costs for these in a manner that is not bound by his usual framework and norms.

Fifth, a change in the role of Camp Humphreys in Pyeongtaek may be sought. The current function of Camp Humphreys is to accommodate large numbers of U.S. reinforcement troops in the event of a Korean Peninsula contingency, making it the largest overseas U.S. "ground forces" base in the world. However, the U.S. has not planned for wars involving large-scale ground forces for over twenty years and, particularly for the defense of allies, demands that the allied nation be responsible for ground operations. In this context, the U.S. may attempt to repurpose Camp Humphreys not for Korean Peninsula contingencies but for China containment. In the event of an armed conflict in the Taiwan Strait, the North Sea Fleet of China, headquartered in Qingdao, would need to pass through the West Sea. At this point, the U.S. could respond with its air force assets or ground-based missiles stationed in South Korea. Efforts could be made to deploy U.S. missiles at Camp Humphreys capable of striking mainland China.

Finally, there is the strengthening of cooperation among South Korea, the U.S., and Japan for China containment. The U.S. may demand expanded military cooperation from South Korea and Japan. In response to a question during his confirmation hearing about "specific measures for trilateral cooperation among South Korea, the U.S., and Japan," Colby replied, "We will focus on developing necessary responses based on the President's missile defense initiative."[21] The Trump administration is building an "Integrated Air & Missile Defense" (IAMD) system to counter the missile capabilities of adversaries, including North Korea. While the primary focus is on defending the U.S. homeland, the possibility cannot be ruled out that South Korea, the U.S., and Japan will establish a missile defense network in the region, ultimately aiming to contain China.

In conclusion, the Trump administration's strategy of linking economy and security with the objective of containing China places a significant burden on U.S. allies. The burden is particularly heavy for South Korea, which is directly exposed to the North Korean nuclear threat and highly dependent on trade with the U.S. Simultaneously, a concerning situation is that, in the perception of the current Trump administration, South Korea is not a core partner in the U.S. Indo-Pacific strategy. In his 36-minute Shangri-La Dialogue speech, Secretary of Defense Hagerty briefly mentioned South Korea only once at the end, as one of the 14 participating countries in rebuilding U.S. defense industry, alongside New Zealand. In contrast, he detailed ongoing military cooperation with the Philippines, Japan, and Australia multiple times. Colby's book also identifies Japan, Australia, and the Philippines as core partners in the Indo-Pacific region, with expanded cooperation with India, while South Korea is not mentioned as a core partner.[23]

Ultimately, it depends on the South Korean government's choice. Depending on the level of participation in the U.S. Indo-Pacific strategy, the U.S. might utilize Japan as its frontline base instead of South Korea. While the U.S. Forces Korea and its bases are an effective deterrent against China, as Commander Brunson put it, serving as an "unsinkable aircraft carrier," [24]they are simultaneously exposed to concentrated Chinese attacks to the same extent. Japan is further to the rear than South Korea, closer to the Taiwan Strait, and hosts the U.S. 7th Fleet's command center, making it a potentially preferred option for the U.S. Chinese naval forces in the Yellow Sea and East China Sea can be targeted by long-range anti-ship missiles deployed in the Kyushu region and the Nansei Islands of Japan. South Korea stands at a crossroads, facing a more difficult and critical choice than ever before.■

[1] Stephen Miran, A User Guide to the U.S. Economic Agenda under the Trump Administration (Council of Economic Advisers, 2025); Stephen Miran, “CEA Chairman Steve Miran Hudson Institute Event Remarks,” The White House, April 10, 2025, https://www.whitehouse.gov/briefings-statements/2025/04/cea-chairman-steve-miran-hudson-institute-event-remarks/.

[2] Stephen Miran, “CEA Chairman Steve Miran Hudson Institute Event Remarks,” The White House, April 10, 2025, https://www.whitehouse.gov/briefings-statements/2025/04/cea-chairman-steve-miran-hudson-institute-event-remarks/.

[3] The original text is as follows: Scott Bessent explains how “tariffs can play a central role” as “a means of leverage for other foreign policy goals, like migration… deterr[ing] military aggression.” Interview cited in American Shipping Company Newsflash, Dec 2024.

[4] The original text is as follows: According to A User’s Guide to Restructuring the Global Trading Systern (2024), Bessent advocated putting countries into “green, yellow and red” groups based on currency policies, trade agreements, security agreements, values, etc., each bearing different tariffs and offering a pathway for countries to shift tiers.

[5] Stephen Miran, A User Guide to the U.S. Economic Agenda under the Trump Administration (Council of Economic Advisers, 2025).

[6] U.S. Department of Defense, Summary of the 2018 National Defense Strategy of the United States of America: Sharpening the American Military’s Competitive Edge (Washington, D.C.: Department of Defense, 2018), 2; U.S. Department of Defense, 2022 National Defense Strategy of the United States of America (Washington, D.C.: Department of Defense, 2022), iii.

[7] Missy Ryan and Alex Horton, “Pentagon’s Secret Memo Prioritizes Taiwan Defense and Homeland,” The Washington Post, March 29, 2025, https://www.washingtonpost.com.

[8] Missy Ryan and Alex Horton, “Pentagon’s Secret Memo Prioritizes Taiwan Defense and Homeland,” The Washington Post, March 29, 2025, https://www.washingtonpost.com.

[9] Missy Ryan and Alex Horton, “Pentagon’s Secret Memo Prioritizes Taiwan Defense and Homeland,” The Washington Post, March 29, 2025, https://www.washingtonpost.com.

[10] Elbridge A. Colby, The Strategy of Denial: American Defense in an Age of Great Power Conflict (New Haven: Yale University Press, 2021)

[11] Pete Hegseth, Remarks by Secretary of Defense Pete Hegseth at the 2025 Shangri-La Dialogue in Singapore (As Delivered), May 31, 2025. U.S. Department of Defense.

[12] Walter Lippmann, U.S. Foreign Policy: Shield of the Republic (Boston: Little, Brown and Company, 1943), 9–10.

[13] Elbridge Colby, testimony before the Senate Armed Services Committee, March 2025

[14] Elbridge Colby, testimony before the Senate Armed Services Committee, March 2025

[15] Elbridge A. Colby, The Strategy of Denial: American Defense in an Age of Great Power Conflict (New Haven: Yale University Press, 2021)

[16] Gen. Xavier Brunson, “The mission of USFK is not solely focused on North Korea,” Land Forces Pacific Symposium (keynote speech, Honolulu, HI, May 15, 2025).

[17] Gen. Xavier T. Brunson, remarks during the ICAS Virtual Spring Symposium Veritas 2025: “Korean Peninsula Issues and US National Security” (online webinar, Institute for Corean American Studies, May 27, 2025).

[18] Missy Ryan and Alex Horton, “Pentagon’s Secret Memo Prioritizes Taiwan Defense and Homeland,” The Washington Post, March 29, 2025, https://www.washingtonpost.com.

[19] Elbridge Colby, testimony before the Senate Armed Services Committee, March 2025

[20] Donald J. Trump, Press Conference by President Trump, Capella Hotel, Singapore, June 12, 2018, transcript, 4:15 P.M. SGT, accessed via White House archives

[21] Elbridge Colby, testimony before the Senate Armed Services Committee, March 2025

[22] Pete Hegseth, Remarks by Secretary of Defense Pete Hegseth at the 2025 Shangri-La Dialogue in Singapore (As Delivered), May 31, 2025. U.S. Department of Defense.

[23] Elbridge A. Colby, The Strategy of Denial: American Defense in an Age of Great Power Conflict (New Haven: Yale University Press, 2021)

[24] Gen. Xavier Brunson, “The mission of USFK is not solely focused on North Korea,” Land Forces Pacific Symposium (keynote speech, Honolulu, HI, May 15, 2025).

■ Author: Park Won-gon_Professor, Department of North Korean Studies, Ewha Womans University

■ Editor: Oh In-hwan_Senior Researcher, EAI; Jeong Jong-hyuk_Researcher, Korea National Diplomatic Academy

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