▶️ The second Trump administration is poised to significantly alter U.S. foreign and security policies, moving away from the rules-based international order and focusing on transactional relationships. This shift poses challenges for U.S. allies, including South Korea.

▶️ South Korea faces tough decisions, including increased defense cost-sharing and navigating potential unilateral U.S.-North Korea agreements. Trump’s America First approach will likely demand more contributions from allies while prioritizing U.S. interests.

▶️ South Korea must proactively address alliance concerns and prepare strategic counteroffers to safeguard its security and economic interests during this critical transition period.

The second Trump administration, which will take office on January 20 next year, is expected to reshape the U.S. into a very different country from what we know today. This is especially true in the area of foreign policy and security affairs dominated by hardline security experts. Trump’s return effectively marks the end of the rules-based international order that was spearheaded by the U.S. after World War II. The free trade system that has contributed to the prosperity of the world economy today will be replaced by tariff barriers. The nuclear umbrella many U.S. allies rely on could be withdrawn unpredictably at the whim of the U.S. president. The promotion of democracy, which has been an important agenda in U.S. foreign policy, will no longer be pursued. In short, Trump’s MAGA movement aims to dismantle the legacy of the ‘benign internationalists’ who have long influenced U.S. foreign policy.

The Republican Party, which won the presidential election by a landslide, has secured control of both the Senate and the House, reflecting a shift in the U.S. political landscape. Regardless of the differences in residence in urban and rural areas, education level, race, and age, Trump’s approval rating has increased significantly compared to the 2020 presidential election. This is a painful point for the Democratic Party, which has continued to compete for presidential elections based on identity, which often relies on ethnic minorities, young people, and women. Economic challenges and illegal immigration were greater voter concerns than the Democratic Party's emphasis on diversity, equity, inclusion (DEI), and political correctness (PC). The election results showed that Trump formed a broad political coalition in U.S. politics and proved that he is no longer a candidate representing deviant political forces. The Republican Party has shown its potential to transform itself from a pro-business, white, highly educated, male-dominated party to a multi-racial, working class-based party.

The next four years will be the era of the Republican Party, or, to be more precise, Trump. Trump, who cannot be re-elected, will push his agenda as much as possible during this period. His intention can be seen from the fast-paced selection process of the Cabinet unlike the first Trump administration. The overwhelming majority of people nominated for high-ranking positions are MAGA believers, Trump loyalists, Washington outsiders, and hardline politicians, rather than those who have been mentioned in the public media. This also has significant implications for Trump-era foreign and security policy on the Korean Peninsula. Mike Waltz, who was nominated as national security adviser, served in Afghanistan as a Green Beret officer in the Army Special Forces. Secretary of State Marco Rubio is considered one of the leading anti-Cuba, anti-China, and anti-Iran figures in the Republican Party. He is also known as a co-sponsor of the North Korean Human Rights Act and a hardliner on North Korea. Pete Hegseth, the nominee for defense secretary, was a former U.S. Army National Guard member who participated in the wars in Afghanistan and Iraq, and was a Fox News host after being discharged from the military as a captain. Tulsi Gabbard, who was nominated for the Director of National Intelligence, has no intelligence-related experience and is known to be tough on Islamic terrorism and North Korea’s nuclear issue but pro-Russian tendencies. In addition, several unexpected high-ranking officials have been nominated or considered. Tesla CEO Elon Musk, who was nominated to co-director of Department of Government Efficiency (DOGE), Robert Kennedy Jr., who was named secretary of Department of Health and Human Services, and Linda McMahon, who was named Secretary of Education, are just a few people expected to be controversial during the Senate confirmation process.

The nominees for foreign affairs and national security are mostly composed of China hawks and hard-liners against North Korea, and are relatively more specialized in the Middle East than the Korean Peninsula. So far, no one who has expertise in the Korean Peninsula or Northeast Asia has been nominated. However, assuming that Trump’s second term high-ranking officials in foreign affairs and national security will faithfully implement Trump’s agenda, South Korea will certainly face tough challenges. The most common concerns for South Korea are an increase in the sharing of defense costs, a direct nuclear deal between the U.S. and North Korea passing South Korea, adjustment of Seoul-Washington trade relations, and demand for South Korean companies to join the trade war on China.

The core of the America First foreign policy is to break away from the existing ‘globalist’ diplomacy. Globalist diplomacy is characterized by endless intervention in international conflicts that are not directly in the U.S. interest, being dragged into endless wars, and placing global institutions and norms above bilateral relations between countries. Trump approaches issues with a transactional mindset, prioritizing deals he perceives as favorable to the U.S. Trump will focus on correcting the imbalance in which the U.S. unilaterally loses money in external relations and only benefits other countries. An imbalance in the economic and trade sectors refers to the U.S. trade deficit, while an imbalance in the military and security sectors refers to insufficient security contributions of U.S. allies, such as insufficient defense burden sharing, and defense spending less than 2 percent of GDP. Korea ranks eighth among the top 10 countries with a trade surplus to the U.S., and Trump always complains that South Korea is a rich country but does not pay enough for its defense.

The first two years of Trump’s second term will be a big challenge for South Korea. If President Trump puts a transactional yardstick on South Korea, South Korea has no choice but to respond from a transactional standpoint as well. Regarding an increase in the defense burden sharing, South Korea needs to raise the share to a certain extent, but needs to think about what it will ask for in return. Considering the size of South Korea’s economy and defense budget, the increased defense burden remains within its financial capacity. South Korea and the U.S. recently signed the Special Measures Agreement on the defense burden sharing (SMA), which will be applied from 2026 to 2030. According to the agreement, South Korean government agreed to increase the contribution of defense costs by 8.3 percent in 2026 to 1.51 trillion won, and decided to increase the contribution in line with inflation going forward. If this agreement is implemented, South Korea’s share of the USFK's defense costs would be approximately 40 percent of the total cost, excluding direct personnel costs. South Korea’s defense budget for 2024 is 59.4 trillion won, and the defense budget for 2025 is 61.58 trillion won, up 3.6 percent from this year’s budget. Korea’s contribution of defense costs for the U.S. Forces Korea in 2026 is merely 2.5 percent of the 2025 defense budget.

While South Korea may be willing to pay more for the costs of U.S. forces in South Korea, setting a precedent of reversing a bilateral SMA agreement based on the word of one man, President Trump, is not desirable for the future of the alliance. Should Trump demand renegotiation, South Korea must approach discussions in good faith while presenting a reasonable counteroffer. Considering such a process as a deal, Korea also needs to draw up a list that it will demand as a counter offer. Key demands include securing the right to enrich uranium for nuclear power plant and reprocess spent nuclear fuel for South Korea’s energy security. South Korea could follow the precedent of the U.S. providing nuclear-powered submarines to Australia under the AUKUS agreement and demand that South Korea be allowed to have nuclear-powered submarines as well. Furthermore, South Korea could ask for joint production of weapons systems and expanded maintenance, repair, and overhaul (MRO) cooperation to strengthen defense cooperation between the two countries.

If a direct nuclear deal between the U.S. and North Korea occurs, South Korea should emphasize the problems of ‘Korea Passing’ and the nuclear domino effect of recognizing North Korea’s nuclear weapons status. On trade policy changes, such as the repeal of the Inflation Reduction Act, South Korea should emphasize that it is an essential economic security and defense cooperation partner for the United States. In response to calls for South Korean companies to join the pressure on China, South Korea should point out that it already cooperates more with the United States than China in key areas such as semiconductors and batteries.

The period between now and the inauguration of President Trump on 20 January 2025 is critically important. During this period, the ROK government should make every effort to convey the current issues of the ROK-U.S. alliance, the security situation, and Korea’s concerns to the Trump camps through special envoys. Although the second Trump term is expected to be more difficult than the first, there is no need to be shaken or discouraged. Trump knows that once he enters the White House, any speed or over-ambition in the early days of his administration will boomerang back in the midterm elections two years later. South Korea must evaluate how much of Trump's campaign rhetoric will materialize into policy and prepare accordingly. Only then can South Korea find opportunity in crisis.