In a historic twist of political fate, former President Donald Trump has reclaimed the US presidency in the 2024 election, this time with a majority in the popular vote and a Congress inclined to support his policy directions. Trump’s return to the White House in January 2025 marks an era of anticipated shifts in US foreign policy, especially as he pursues his stated goals with fewer obstacles. While Europe, and specifically US aid to Ukraine, will feel the brunt of Trump’s immediate foreign policy ambitions, one of the most unexpected impacts could be in Northeast Asia, particularly in South Korea.
Throughout his first presidency (2017–2021), Trump’s attitude toward South Korea appeared markedly strained. Accounts from former White House staff reveal a personal aversion to then-South Korean President Moon Jae-in, which often reflected in Trump’s policy stances. He reportedly threatened to “blow up” the US-South Korea alliance if he won re-election in 2020. Trump frequently criticized the expense of joint military exercises between the US and South Korea, expressing frustration over what he perceived as South Korea’s insufficient financial contributions toward shared defense costs. Additionally, he reportedly labeled South Koreans as “terrible people,” underscoring his contempt for aspects of the alliance.
This history suggests that Trump may once again prioritize South Korea’s defense spending and possibly aim to renegotiate alliance terms in a way that places additional financial strain on Seoul. Trump has long held the view that allies should shoulder more responsibility for their defense costs, with South Korea as a primary target. His recent comments referring to South Korea as a “money machine” and calling for a ninefold increase in South Korea’s payments for US troop presence have sparked fears that he may soon reopen contentious alliance talks, placing new demands on an already fragile alliance.
In stark contrast to his rocky rapport with South Korea, Trump displayed a peculiar affinity for North Korean leader Kim Jong Un during his first term, cultivating what he described as a “bromance.” His summits with Kim — one in Singapore in 2018 and another in Hanoi in 2019 — though yielding limited concrete results on denuclearization, marked a sharp break from traditional US policy toward North Korea. While Kim’s authoritarian control and nuclear ambitions have led to widespread condemnation, Trump openly praised Kim’s leadership style, even admiring how Kim’s aides would jump to attention in his presence.
This apparent favoritism for North Korea’s autocratic regime over the democratic government of South Korea sent a mixed message to allies and adversaries alike, raising concerns over Trump’s loyalty to traditional US alliances. Trump’s return to office, coupled with his demonstrated admiration for autocratic leaders, could lead to a policy shift that further destabilizes the US-South Korea alliance. If Trump opts to engage North Korea in high-level negotiations once more, the US may be seen as sympathizing with one of the world’s most oppressive regimes over a longstanding ally.
A major point of contention during Trump’s previous tenure was his insistence on South Korea paying more for the stationing of US forces on the Korean Peninsula. This tension has resurfaced with Trump’s renewed calls for South Korea to contribute far more financially, recently stating that he wants South Korea to pay up to nine times what it currently contributes. Unlike NATO allies, who can negotiate collective defense funding, South Korea stands more isolated in Northeast Asia.
South Korea’s location makes it highly vulnerable, bordering three nuclear-armed states: North Korea, China, and Russia. Moreover, historical tensions with Japan continue to complicate regional relations, particularly given the legacy of Japanese imperialism during World War II. With little regional support and a renewed, more costly alliance under Trump, South Korea may face tough decisions that strain its domestic political landscape.
For President Yoon Suk Yeol’s administration, navigating these demands will likely be a challenging balancing act. While South Korean conservatives may feel compelled to meet Trump’s financial terms to avoid an alliance fallout, the country’s left-leaning opposition would likely exploit this as evidence of government subservience to US demands, further dividing public opinion. Already, Yoon’s approval rating is at an all-time low of just 19 percent, signaling a lack of public support for a potentially costly renegotiation with Trump.
Given Trump’s previous term’s dynamics, there has been growing debate in South Korea about exploring an independent nuclear capability as a form of “self-insurance” in case the US security guarantee weakens under Trump’s administration. Public support for a South Korean nuclear program has been strong for over a decade, with proponents arguing that a nuclear deterrent would secure the nation against threats from North Korea and possibly China. Until now, resistance from both the US and China has been a formidable barrier to such an initiative.
However, Trump’s willingness to engage in potentially transactional diplomacy with allies casts doubt on the strength of America’s commitment to defend South Korea. Under the Biden administration, Washington consistently reaffirmed its commitment to South Korea’s security despite North Korea’s nuclear capabilities. Yet, the Trump administration’s approach has left South Korea questioning whether the US would “sacrifice San Francisco for Seoul.” With Trump’s re-election, the question has resurfaced, and many analysts believe Trump’s answer would lean toward “no.”
South Korea’s pivot towards nuclearization may seem drastic but could appear increasingly reasonable in light of Trump’s apparent lack of commitment to the alliance. While acquiring an independent nuclear capability would carry diplomatic risks, particularly with China and Japan, South Korean policymakers could see it as a necessary step if Trump’s demands remain high and the US security guarantee appears unreliable.
In the wake of Trump’s victory, South Korean President Yoon Suk Yeol reached out to Trump in a 12-minute congratulatory call, expressing hope for a positive working relationship. During the call, the leaders reportedly agreed to arrange an in-person meeting soon, with Trump noting the importance of “good cooperative relations” between the two nations.
Yoon’s approach mirrors that of other leaders who have sought to engage Trump personally, understanding that his foreign policy decisions often reflect personal sentiments rather than broader strategic calculations. Given Trump’s history of building foreign policy around personal relationships, Yoon may be betting on his ability to form a positive rapport with Trump, circumventing some of the difficulties his predecessor Moon Jae-in faced.
The stakes are high. By adopting a conciliatory approach, Yoon hopes to reduce the likelihood of antagonistic demands and foster a more favorable negotiation environment. However, Trump’s unpredictability remains a factor that complicates any long-term planning. Yoon’s optimism may hinge on his ability to flatter Trump and sidestep the more contentious issues that strained Trump’s previous interactions with South Korean leadership.
Trump’s renewed presidency signals a period of instability for America’s global alliances. If he begins withdrawing support from established allies, as anticipated with Ukraine, other US partners may start questioning the durability of their own relationships with Washington. For South Korea, this challenge is compounded by the broader geopolitical situation in Northeast Asia, where China’s influence grows steadily, and North Korea’s provocations remain constant.
At a broader level, Trump’s focus on cutting costs could reshape America’s military posture worldwide, potentially scaling back US forces in strategic regions like the Korean Peninsula. His administration has already shown a willingness to reduce the US footprint abroad, and there are concerns that he might push for a similar outcome in South Korea. Should Trump withdraw even a portion of the 28,500 US troops stationed there, South Korea would be forced to reassess its defense posture.
In response, South Korea might seek alternative security partnerships, explore arms agreements with other nations, or even strengthen ties with China. Each of these scenarios presents complex diplomatic challenges, particularly as South Korea tries to maintain a balance between its alliance with the US and its geographical and economic reality in Asia.
As Trump prepares for his second term, the US-South Korea alliance stands at a crossroads. Trump’s re-election presents both challenges and opportunities for Seoul, which will need to navigate an array of potential policy changes. South Korea’s reliance on the US for security and economic stability has defined its foreign policy for decades, but Trump’s return to power could push South Korea to explore more independent or even radical measures, such as developing its own nuclear deterrent.
In his remaining time as president, Yoon may attempt to foster a strong personal connection with Trump, banking on Trump’s preference for leader-to-leader diplomacy to safeguard South Korea’s interests. However, given Trump’s volatile approach to international relations, any assurances Yoon receives could be subject to change.
The world is watching as Trump’s foreign policy unfolds. As one of America’s critical allies in Asia, South Korea’s future stance could signal a shift in the region’s balance of power. How Trump chooses to engage with Seoul in the coming years could reshape not only the US-South Korea alliance but also the broader geopolitical landscape in Asia. Whether Yoon’s optimism will be met with reciprocated goodwill or reinforced demands remains to be seen, but the next four years are poised to be some of the most consequential in recent memory for the US-South Korea relationship.
