Key takeaways:

- The new U.S.–ROK fact sheet reveals a highly transactional alliance, with economic deals and investment commitments taking precedence over traditional security guarantees.

- While Washington reaffirmed extended deterrence and welcomed Seoul’s increased defense spending, major modernization issues — including strategic flexibility — remain ambiguous, even as the two sides explore politically charged cooperation on nuclear-powered submarines.

- The future of the alliance will hinge on whether Seoul and Washington can balance commercial demands with credible long-term defense planning in an increasingly contested Indo-Pacific.

On November 13, 2025, the White House released a joint fact sheet offering the clearest window yet into the state of U.S.-South Korea relations and how the second Trump administration envisions the future of the alliance. The delayed release of the fact sheet, which appeared two weeks after U.S. President Donald Trump’s October 29 meeting with South Korean President Lee Jae-myung in Gyeongju, and more than two months after their first summit meeting in Washington DC on August 25, hinted at ongoing economic and security challenges in the bilateral relationship. Despite the delay, the highly anticipated fact sheet was welcomed by stakeholders to the alliance. It clarified U.S. reductions in reciprocal tariffs on South Korean goods to 15%, and presented a path forward for structuring South Korea’s $350 billion investment package to the United States. However, the fact sheet also left open-ended several questions related to alliance modernization, even as it introduced new opportunities (and challenges) for cooperation including U.S. support for South Korea’s development of nuclear-powered attack submarines. Three broad takeaways from the joint fact sheet and their implications for the U.S.-South Korea alliance stand out.  

The Transactional and Commercial Nature of the Alliance

The first takeaway is the emphasis on economic relations and commercial investments which, according to the fact sheet, “reflects the strength and endurance of the U.S.-ROK alliance.” Updates on the economic relationship were placed upfront and comprised nearly two-thirds of the entire fact sheet. More concretely, the sections addressing critical industries, commercial ties, foreign exchange market stability, trade, and economic prosperity included 1,293 words - twice the length of the sections covering security and defense issues which comprised only 622 words. The emphasis on economic cooperation aligns with the prevailing narrative that President Trump values allies for their commercial as much as (if not more than) their security benefits, even when alliances grounded in mutual defense treaties—such as the U.S.–ROK alliance—have traditionally centered on defense ties. The fact sheet also reinforces the extractive nature of the Trump administration and echoes the White House’s October 29 fact sheet touting Trump’s foreign investment deals under the heading, “President Donald J. Trump Brings Home More Billion Dollar Deals During State Visit to the Republic of Korea.”

The transactional nature of the alliance and U.S. commercial gains were even cited in sections of the joint fact sheet intended to underscore U.S. defense commitments. For instance, when outlining U.S.-ROK alliance modernization, the two governments added South Korea’s commitment to spend “$25 billion on U.S. military equipment purchases by 2030” and shared plans to provide “comprehensive support” for U.S. Forces, Korea (USFK) “amounting to $33 billion in accordance with ROK legal requirements.” Likewise, U.S. support for the transfer of wartime operational control (OPCON), and South Korea’s pledge to strengthen its own military capabilities in preparation for OPCON, entailed the “acquisition of advanced U.S. weapons systems and the expansion of bilateral defense industrial cooperation.”

Economic and security issues are of course interlinked in the new geopolitics of Asia. Expanding the U.S. industrial defense base and deepening defense industrial cooperation remain critical to alliance modernization as attested by South Korea’s pledge to invest $150 billion in the U.S. shipbuilding sector. The upshot has been a renewal of the U.S.–South Korea alliance, as Lee’s pragmatic response to Trump’s transactional demands has helped bolster South Korea’s standing as a “model ally” in the eyes of the Trump administration. However, the administration may continue to leverage the U.S.–ROK alliance for commercial gain without any guarantee that South Korea’s investments will yield longer-term economic or security benefits.

Alliance Modernization and Defense Cooperation

The second takeaway concerns both what was stated—and what was left unstated—about existing defense and security commitments between the two allies. Perhaps most important for South Korea is the Trump administration’s reaffirmation of U.S. extended deterrence, along with its commitment to strengthen consultation mechanisms such as the Nuclear Consultative Group. For the United States, South Korea’s commitment to increase its defense spending to 3.5% of GDP—the first non-NATO ally to make such a pledge—– drew recognition from the Trump administration including U.S. Under Secretary of Defense Elbridge Colby.

Prior to the August 25 summit, experts anticipated that the Trump administration would press Lee to expand South Korea’s alliance responsibilities to the broader Indo-Pacific and reaffirm the concept of strategic flexibility by permitting USFK to participate in activities beyond the Korean Peninsula. To this end, the two governments agreed to “enhance U.S. conventional deterrence posture against all regional threats to the Alliance, including the DPRK.” However, the fact sheet made no direct mention of strategic flexibility, even though Seoul has accepted the idea of USFK deployments outside the Korean Peninsula in theory, if not in practice. Instead, the two governments referenced the loosely defined understanding of strategic flexibility established by Washington and Seoul in 2006. The omission of the term was likely a U.S. concession to avoid invoking a phrase that might provoke Beijing and draw negative reactions from Lee’s progressive base wary of dragging South Korea into a potential conflict with China in the Taiwan Strait.

Cooperation on nuclear-powered submarines

The third takeaway is the prospect for cooperation on shipbuilding, particularly on nuclear-powered submarines (SSNs) as mentioned at the end of the fact sheet. President Lee’s reference to SSNs and his request to President Trump to provide nuclear fuel were unexpected from the American side. Equally surprising was President Trump’s willingness to help South Korea pursue SSNs, in part because  U.S. naval analysts have argued that developing nuclear-powered attack submarines would offer only limited advantages over South Korea’s existing and planned anti-submarine warfare capabilities, while imposing significant financial and opportunity costs, making an SSN fleet an “unnecessary luxury, not an actual military requirement” for operations around the Korean Peninsula.

The strategic considerations on the U.S. side have less to do with deterring North Korean or Chinese submarines in the near term—since SSNs not be deployable for another 10 to 15 years—and more to do with defense resilience and expanding the U.S. defense industrial base with allied participation. If Washington is thinking about long-term challenges in the Indo-Pacific and beyond, there may be a strategic rationale for enabling allies to acquire nuclear-powered submarines as part of a broader effort to maintain deterrence against an expanding Chinese PLAN fleet over the medium to long term. Permitting South Korea to pursue nuclear-powered submarines may also help shift the Republic of Korea Navy’s mindset from focusing solely on defense and deterrence around the Korean Peninsula to undertaking broader missions across the Indo-Pacific—though this is unlikely to reflect how South Korea currently envisions using SSNs.

However, commercial and political reasons may have outweighed strategic factors behind the Trump administration’s decision to green light the development of South Korean SSNs. Trump’s initial instinct was to propose building submarines at Philly Shipyard, reflecting his business-oriented mindset, despite the shipyard lacking the capacity to produce nuclear submarines. Implicit in President Lee’s request for SSNs is the idea that South Korea would assume greater responsibility for deterring both North Korea and China in line with the Pentagon’s call for allies to take on more of the regional defense burden share. The Trump administration may therefore see South Korean SSNs as an economic and political win when framed as: 1) an investment opportunity for the United States that also creates jobs for Americans; 2) a way to strengthen the U.S. defense industrial base; and 3) a means of encouraging allies to bolster their own defense capabilities and assume a larger security role in their region.

As the United States and South Korea navigate an evolving geopolitical landscape, their ability to balance economic priorities with credible defense modernization will determine whether the alliance can meet the strategic challenges of the coming decade.