Korea Policy Vol. 3, Issue 2

The U.S.-South Korea partnership is being challenged by the uncertainty of both nations’ Indo-Pacific policies, competing national objectives, and U.S. President Donald Trump’s willingness to risk long-standing alliances in favor of transactional economic gains. While the alliance has successfully weathered previous crises, the bilateral relationship may be facing its greatest challenge yet as Washington is more willing to force Seoul to conform to U.S. priorities. 

The election of President Lee Jae Mung brought an end to South Korea’s monthslong political upheaval triggered by predecessor Yoon Suk Yeol’s imposition of martial law and subsequent impeachment. However, competing factions within the Lee administration advocate conflicting foreign policies, leading to potential ambiguity surrounding the country’s future direction. 

President Lee will attempt to maintain South Korea’s traditional balancing of its relationships with its security guarantor the United States and its largest trading partner China while attempting to alienate neither. Lee is caught between Scylla and Charybdis, trying to simultaneously accommodate the Trump administration’s more forceful efforts to forge allies into an anti-China coalition while minimizing the risk of retaliation by China.  

The Trump administration’s Indo-Pacific policy remains bereft of details. The degree to which the United States will play an overseas security role remains an unresolved debate among administration officials as well as the broader conservative movement.  

Traditional Reaganite interventionist hawks have been replaced in the Republican Party by prioritizers, constrainers, and neo-isolationists. This, along with President Trump’s willingness to use tariffs as cudgels against economic partners, has caused U.S. allies to increasingly question the viability of U.S. security guarantees and commitment to its defense treaties. 

U.S. Demands More, Promises Less in Alliance. Having browbeaten South Korea into a disadvantageous trade deal that violates the Korea-U.S. Free Trade Agreement (KORUS) that Trump had previously renegotiated, the United States demanded security concessions as well. Washington pushed Seoul to increase South Korean defense expenditures both as a percentage of the country’s GDP and through greater contributions to offset the cost of stationing U.S. forces on the Korean Peninsula. 

The Trump administration advocates modernizing the alliance by reorienting the primary mission of U.S. forces in South Korea toward the China threat. Doing so will require South Korea to assume greater responsibility for countering the North Korea threat and the United States to potentially redeploy some of its forces elsewhere in the region. 

Two U.S.-South Korea leaders’ summits provided both major announcements and continued uncertainty due to differing depictions of what was agreed to. U.S. and South Korean post-summit security statements are a Rorschach test subject to interpretation over how significant a change they represent from previous bilateral agreements on strategic flexibility, the role of United States Forces Korea (USFK) in regional contingencies, and the potential for transferring wartime operational control (OPCON) of South Korean forces from the U.S.-led Combined Forces Command (CFC). Contrary to earlier indications, there does not appear to be a reorientation of primary USFK responsibility toward Taiwan scenarios nor any public South Korean commitment to a supporting role in defending Taiwan. 

U.S. Stymied on Outreach to North Korea. While the Trump administration will quickly come into conflict with Lee’s conciliatory approach toward China, the two leaders will find greater alignment on their mutual desire for engaging North Korea. But North Korea has rejected all U.S. and South Korean entreaties for dialogue since the last U.S.-North Korean diplomatic engagement in October 2019. Although Trump touts his friendship with North Korean leader Kim Jong Un, North Korean diplomats in New York repeatedly refused to accept his letter seeking to reopen dialogue with Kim, nor did they accept Trump’s request for a meeting during his October 2025 trip to South Korea.  

The North Korean leader sees little need to engage with the United States, since he is receiving far greater benefits from Russia with fewer conditions than he could possibly attain from the United States. Russia’s largesse in return for North Korea providing massive amounts of military equipment enables North Korea to mitigate the impact of international sanctions, as does Kim’s lucrative cybercurrency crimes.  

Tempestuous Time for the Alliance. As both the United States and South Korea find their footing on their Indo-Pacific strategies, South Korea’s new leadership will be tested by the deteriorating regional security environment, U.S. demands for greater security contributions, and a U.S. trading partner that poses a more immediate economic threat than China. 

The United States needs allies and partners to economically compete with and militarily confront the multi-faceted China threat. But Washington has instead alienated potential collaborators and undermined collective action by threatening its allies, demanding avaricious security payments, and imposing capricious and excessive tariffs. The United States has exacerbated allied fears of abandonment by introducing strategic ambiguity as to whether it will uphold its treaty commitments to defend its allies.  

The United States should well remember Winston Churchill’s famous maxim, “The only thing worse than fighting with allies is fighting without them.”