Six months into President Donald J. Trump’s second term, the world is witnessing unprecedented developments. Trump is aggressively pressing U.S. allies and friendly nations in the two major domains of economy and security, typified by tariffs and defense cost-sharing. This article aims to analyze the Trump administration’s foreign policy and alliance policy, and to assess the repercussions for the ROK-U.S. alliance.

Trump Administration’s Foreign Policy Stance

1) Linkage of Economy and Security

The core of the Trump administration’s second-term foreign policy focuses on containing China, and to achieve this priority, linking security and economy to demand increased responsibility and burden-sharing from allies and like-minded nations. Stephen Miran, the current Chairman of the White House Council of Economic Advisers, diagnoses that while the U.S. has acted as a "benign hegemon," providing public goods in the international economy and security, excessive costs have been imposed on the U.S. for providing them. Miran particularly highlights the phenomenon of the U.S. financial burden becoming disproportionately heavy, arguing that the dollar’s function as the reserve currency has led to persistent currency distortions; he criticizes some countries for intentionally devaluing their currencies to maintain a strong dollar, thereby securing trade competitiveness. As a solution, he asserts that the U.S. should no longer permit the "free riding" of other nations that have utilized U.S. security and economic public goods. He prescribes that the U.S. manage exchange rates and leverage tariffs to revive American manufacturing. [1]

In this process, emphasis is placed on burden-sharing by allies and friendly nations through the linkage of security and economy. For the U.S. to continue providing public goods in security and economy as a "hegemon," an improvement in international burden-sharing is necessary. Should other nations desire the benefits of the U.S. security and financial umbrella, they must share the responsibility, thereby alleviating the burden on the American people. [2] U.S. Treasury Secretary Scott Bessent also responded to this, declaring that "tariffs should be utilized as a means of foreign policy and national security." Specifically, he argues that "nations should be categorized into Green (friendly), Yellow (neutral), and Red (competitor) groups according to their monetary policy, trade agreements, security agreements, and values." [3] Different tariff rates would apply to each group, and conditions and pathways for nations to ascend to higher groups should also be presented. [4]

It is also emphasized that combining tariff barriers with security commitments should compel allies and like-minded nations to participate in the containment of China. Miran elaborates, "From the U.S. perspective, it is not a loss even if other nations choose to maintain their current China policy and accept high U.S. tariffs. Within this system, paying high tariffs provides tax revenue to the U.S. while simultaneously reducing U.S. security burdens." [5] In essence, he warns that if allies do not augment security burden-sharing to contain China, they will face high tariffs and a reduction or withdrawal of U.S. defense commitments.

2) Containing China

The U.S. officially began prioritizing its response to the China threat during the Barack Obama administration. Subsequently, both the 2018 and 2022 National Defense Strategies (NDS), published during the first Trump administration and the Biden administration, respectively, explicitly stipulated that the People's Republic of China presents the most significant challenge to the U.S. Department of Defense. [6]

Following the first Trump administration, the second administration is heavily highlighting the China threat and emphasizing a robust response. The U.S. Department of Defense’s Interim National Defense Strategic Guidance, reported by U.S. media at the end of March, posits China’s threat as the “only pacing threat.” [7] A pacing threat signifies the core threat that the U.S. Department of Defense employs as a basis when planning and implementing military strategy, force composition, weapons development, budget allocation, and training. The guidance identifies the denial of a fait accompli occupation of Taiwan and the defense of the U.S. homeland as the Department’s sole pacing scenario. While both the first Trump administration and the Biden administration designated China as the greatest U.S. threat and deployed forces in preparation for conflict in the Indo-Pacific region, this new guidance regards the Taiwan invasion scenario as the exclusive and paramount concern, reorienting the "entire U.S. military" to the Indo-Pacific region. Accordingly, the guidance formulates plans based solely on a war with China in terms of military structure and resource planning concepts and clearly articulates its stance to delegate 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, alliances are being calibrated accordingly. First, Trump explicitly demands the sharing of roles, responsibilities, and burdens from allies and friendly nations. Last March, the Interim National Defense Strategy Guidance stated, “Considering the limitations of U.S. personnel and resources, risks will be taken 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] Elbridge Colby, the Under Secretary of Defense for Policy, wrote in his 2021 book, "The U.S. cannot deter China alone, so Asian allies must enhance their own defensive capabilities and strengthen cooperation with the U.S." [10] In late May, U.S. Secretary of Defense Hegseth presented two core demands to Indo-Pacific regional allies and like-minded nations at the Shangri-La Dialogue. [11] First is a substantial increase in responsibility and burden-sharing. Hegseth sharply criticized that it “makes no sense” for Asian countries, exposed to the North Korean threat and a more potent Chinese threat, to spend less, when even NATO countries in Europe are pledging to spend 5% of their Gross Domestic Product (GDP). This statement can be interpreted as a signal that South Korea’s 2.8% defense expenditure relative to GDP in 2025, while being on the frontline of the North Korean threat, is also considered insufficient. Second, he unequivocally stated that "security dependence on the U.S. and economic dependence on China (安美經中)" is unacceptable. Hegseth underscored, "Economic dependence on China not only intensifies their malicious influence but also complicates our (U.S.) defense decision-making space when tensions escalate." As mentioned earlier, it was reaffirmed that the U.S. can leverage tariffs to pressure allies for increased defense cost-sharing and responsibility by linking economic and security interests. In essence, allies are being called upon to participate in both security and economic domains for the containment of China.

The U.S. alliance transformation as described above can be projected onto the ROK-U.S. alliance as follows: first, Korean Peninsula defense may be Koreanized. It cannot be ruled out that South Korea will assume primary responsibility for responding to North Korea’s conventional threats, while the U.S. provides extended deterrence against North Korea’s nuclear weapons. The U.S., aiming to concentrate on the Indo-Pacific region, ultimately China, seeks to reduce its burden regarding North Korea’s conventional threats. This is also a means to resolve the "Lippmann Gap" that Colby highlighted at his Senate confirmation hearing in March. The Lippmann Gap signifies the imbalance between a nation’s diplomatic 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, asserting that "on the one hand, what we (the U.S.) seek to accomplish in the world, and on the other hand, the resources and political will to achieve those goals, are severely mismatched." [13] Currently, the U.S. faces multi-dimensional conflicts but is inadequately prepared, implying that allies should assume responsibility for their own defense. Accordingly, attempts to substantially reduce the U.S. responsibility for South Korea’s defense cannot be ruled out.

Second, early transfer of wartime operational control (OPCON) may be pursued. This would be a U.S. choice to transfer OPCON early to South Korea to mitigate its defense responsibility and burden, and to maximize the strategic flexibility of U.S. Forces Korea (USFK) for China containment. Colby has also repeatedly expressed his desire for OPCON to be transferred to South Korea. When questioned about OPCON transfer at his Senate hearing, he responded, "I believe President Trump’s foreign policy vision includes empowering more capable and willing allies like South Korea, and therefore I support efforts to strengthen South Korea’s role within the alliance." [14] In his own book, he stated more explicitly, "As a U.S. ally, I support OPCON transfer to expand South Korea’s defense responsibility." [15] Since South Korea’s Lee Jae Myung government also presented OPCON transfer as one of its presidential campaign pledges, the likelihood of an early implementation by both the ROK and U.S. sides has increased. The core issue ultimately is to realize the large-scale projection of U.S. forces in the event of a contingency on the Korean Peninsula. According to existing ROK-U.S. joint operations plans, a substantial reinforcement, including U.S. ground forces, is known to occur upon the outbreak of war on the Korean Peninsula. However, the U.S. has been conducting wars primarily with air and naval forces, striking deep into enemy’s territory, and minimizing ground operations. Therefore, the actual forces to be mobilized in a Korean Peninsula contingency are limited. The U.S. may reorganize the Combined Forces Command system and transfer OPCON to enable South Korea to function as the principal actor in conducting war during a Korean Peninsula contingency.

Third, the role, scope, and scale of USFK may be adjusted. Its operational scope may extend from its existing focus on deterring North Korean threats to cover the Indo-Pacific region, targeting China. The U.S. will likely seek to integrate and utilize forward-deployed forces in the Indo-Pacific region if a conflict arises there. For example, in a Taiwan Strait crisis, all available and operational forces from USFK and USFJ would be mobilized. This implies that USFK will no longer be confined to deterring North Korean threats. While current forces may not be optimal for projection outside the Korean Peninsula, there is a possibility of reorganization in this direction. Recently, USFK Commander Xavier Brunson declared the expanded role of USFK, stating, "The role of USFK is not solely focused on repelling North Korea," [16] and "To maintain peace through strength, we sometimes have to move to other regions." [17] Previous commanders had exclusively limited USFK’s role to the North Korean threat.

Fourth, the Trump administration may provide extended deterrence to South Korea but link it to cost considerations. The Interim National Defense Strategic Guidance illuminated the principle of providing nuclear deterrence by stating, "The U.S. would provide nuclear deterrence against Russia, but forces needed for homeland defense or China containment will not be available for NATO." [18] Colby also responded to a hearing question regarding U.S. extended deterrence provision, saying, "I recognize that U.S.-ROK alliance is extremely important, and we face a severe threat from North Korea.... Therefore, the strategic deterrence and defense posture of both the U.S. and ROK must be reliable and robust." [19] However, uncertainty persists because Trump has shown personal interest in demanding financial contributions from South Korea for strategic asset deployment and combined exercises, which are essential for extended deterrence, since his first term. Specifically, starting with a press conference immediately following the U.S.-DPRK Singapore agreement in June 2018, [20] Trump has publicly expressed his perception of ROK-U.S. combined exercises as "expensive," "provocative," and "war games." Therefore, he may demand the contribution of those costs in his unique, unconventional manner.

Fifth, a change in the role of Camp Humphreys in Pyeongtaek may be explored. Camp Humphreys’ current function is to accommodate a large-scale U.S. reinforcement in the event of a Korean Peninsula contingency, making it the world’s largest overseas U.S. "ground forces" base. However, for over two decades, the U.S. has not planned wars involving large-scale ground forces and particularly demands that allied nations assume responsibility for ground operations for their own defense. Consequently, the U.S. may attempt to repurpose Camp Humphreys’ function from Korean Peninsula contingency preparation to China containment. If armed conflict erupts in the Taiwan Strait, China's North Sea Fleet, headquartered in Qingdao, must traverse the West Sea (Yellow Sea) for deployment. In such a scenario, the U.S. could respond with USFK air assets or ground-to-ship missiles. The deployment of missiles targeting mainland China at Camp Humphreys may be pursued.

Lastly, ROK-U.S.-Japan cooperation may be strengthened for countering China. The U.S. may demand expanded military cooperation from South Korea and Japan. Colby, when queried about "concrete measures for ROK-U.S.-Japan trilateral cooperation" at his confirmation hearing, replied, "We will concentrate on formulating necessary countermeasures based on the President's missile defense initiative." [21] The Trump administration is establishing an Integrated Air & Missile Defense (IAMD) to counter the missile capabilities of adversarial nations, including North Korea. While primarily focused on U.S. homeland defense, the possibility of South Korea, the U.S., and Japan constructing a regional missile defense network to ultimately pursue China containment cannot be ruled out.

In conclusion, the Trump administration’s economic-security linkage strategy aimed at China imposes a substantial burden on U.S. allies. The burden on South Korea, which is directly exposed to the North Korean nuclear threat and highly dependent on trade with the U.S., is particularly significant. Concurrently, 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 speech, Secretary of Defense Hegseth mentioned South Korea only once at the very end, alongside New Zealand, as merely one of 14 participating nations for rebuilding the U.S. defense industry. In contrast, the Philippines, Japan, and Australia were repeatedly and specifically elaborated upon regarding ongoing military cooperation. [22] Colby's book also states that the U.S. core partners in the Indo-Pacific region are Japan, Australia, and the Philippines, and that cooperation with India should be expanded, without mentioning South Korea as a core partner. [23]

Ultimately, it rests on the choice of the South Korean government. Depending on the level of South Korea’s participation in the U.S. Indo-Pacific strategy, the U.S. may utilize Japan, rather than South Korea, as a frontline base. USFK and its bases, as Commander Brunson expressed, are effective as "unsinkable aircraft carriers" for China containment, [24] but concurrently, they are exposed to concentrated Chinese attacks to the same extent. Japan is geographically positioned behind South Korea, closer to the Taiwan Strait, and hosts the U.S. 7th Fleet Command, making it potentially preferred from the U.S. perspective. Chinese fleets in the West Sea (Yellow Sea) and East China Sea can be targeted by long-range ground-to-ship missiles deployed in Japan's Kyushu region and the Nansei Islands. South Korea stands at a crossroads of choices more arduous and momentous than ever. ■

References

Bessent, Scott. 2024. Interview cited in American Shipping Company Newsflash, December 2024.

Brunson, Xavier. 2025. “The mission of USFK is not solely focused on North Korea.” Keynote speech at the Land Forces Pacific Symposium, Honolulu, HI, May 15, 2025.

Brunson, Xavier T. 2025. 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.

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

Colby, Elbridge. 2025. Testimony before the Senate Armed Services Committee, March 2025.

Hegseth, Pete. 2025. 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.

Lippmann, Walter. 1943. U.S. Foreign Policy: Shield of the Republic. Boston: Little, Brown and Company.

Miran, Stephen. 2025. “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/.

Miran, Stephen. 2024. A User’s Guide to Restructuring the Global Trading System. Hudson Bay Capital.

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

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

Trump, Donald J. 2018. Press Conference by President Trump, Capella Hotel, Singapore, June 12, 2018. Transcript, 4:15 P.M. SGT. Accessed via White House archives.

U.S. Department of Defense. 2022. 2022 National Defense Strategy of the United States of America. Washington, D.C.: Department of Defense.

U.S. Department of Defense. 2018. 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.

[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] According to the transcript, 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] According to A User’s Guide to Restructuring the Global Trading System (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 Posthttps://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).

■ Won Gon Park is Chair of EAI’s Center for North Korea Studies and a professor of North Korean Studies at Ewha Womans University.

■ Translated and edited by Inhwan OH, EAI Senior Research Fellow; Jong Hyuk CHUNG, Research Associate, Korea National Diplomatic Academy;Julia Natasza LASIOTA, Intern
    For Inquiries: 02-2277-1683 (ext. 202) ihoh@eai.or.kr