Moon Chung-in, professor emeritus of Yonsei University, speaks during an interview with The Korea Times at the newspaper's office in central Seoul, Feb. 4. Korea Times photo by Choi Won-suk

As anticipated, U.S. President Donald Trump has embarked on a series of bold moves that are set to reshape the global landscape. Recent actions following his Jan. 20 return to office, such as imposing stiff tariffs and pursuing controversial acquisitions of territories like Greenland, the Panama Canal and the Gaza Strip, signal a return to the business-like, deal-driven approach that Trump champions. Under this administration, even traditional allies like South Korea may not be immune to its aggressive foreign policy stance.

For South Korea, Trump's transactional approach poses a particular challenge, as it may disrupt the longstanding ironclad alliance between the two nations. Moon Chung-in, a political analyst, and James Laney, a distinguished professor at Yonsei University, predict that under Trump's second presidency, the South Korea-U.S. alliance could experience significant, if not radical, shifts.

In an exclusive interview with The Korea Times on Feb. 4, Moon explained his analysis of the likely consequences of a Trump-led U.S. on South Korea's foreign policy, particularly in the realms of defense, trade and security. He cited the need to adopt the idea of "thinking the unthinkable" such as "The Korean Peninsula without the U.S. and U.S. troops."

Below is an excerpt of The Korea Times interview with Moon. It has been edited for clarity and readability.

Q: What do you expect from Trump's second term in office, particularly in terms of foreign policy?

A: As expected, Trump has shown his aggressive and highly transactional approach. His policies will disrupt global dynamics, especially for countries like South Korea that have been longtime allies of the U.S. In this new era, Trump will not hesitate to leverage his "America First" agenda to maximize U.S. interests, which could undermine decades of cooperation. For South Korea, this means facing profound strains in the alliance that have long been viewed as unshakeable.

Q: What are the primary challenges South Korea faces in maintaining its alliance with the U.S. under Trump?

A: There are three key issues that could put a significant strain on the South Korea-U.S. relationship during Trump's second presidency.

First, we may see a renewed dispute over defense cost-sharing. Under the Joe Biden-Yoon Suk Yeol governments, South Korea agreed to contribute $1.1 billion annually to defense costs starting in 2026, with an 8 percent increase planned for 2025. However, Trump has recently insisted that South Korea should pay at least $10 billion annually. It cannot be ruled out that he could reduce or even withdraw its military presence in South Korea as leverage in these negotiations, which could trigger anti-American sentiments in the country.

Second, there is a divergence in threat perceptions. Trump's focus will likely be on building effective deterrence against China, rather than North Korea. Meanwhile, South Korea's priority remains deterring threats from the North. This misalignment will test the strength of the alliance, especially as South Korea is also increasingly concerned about the security situation in the Taiwan Strait and South China Sea.

Lastly, the issue of nuclear deterrence will be a flashpoint. Trump's "America First" logic suggests that he may not prioritize the defense of South Korea at the cost of American territories like Hawaii or Los Angeles. This could weaken U.S. commitments to extended nuclear deterrence for South Korea, potentially prompting Seoul to reconsider its own nuclear ambitions. Such a move could lead to a nuclear arms race in Northeast Asia — a deeply concerning scenario.

Q: How will Trump's tariff policies impact South Korea?

A: Trump's tariff war is coming for South Korea. As one of the U.S.' largest trade surplus countries, South Korea is likely to become a target for Trump's protectionist policies. In 2024, South Korea recorded a trade surplus of nearly $60 billion with the U.S., and Trump may seek to correct the trade deficit by imposing new tariffs or renegotiating the U.S.-Korea Free Trade Agreement (KORUS FTA).

New tariffs on key sectors like semiconductors, automobiles and steel could have devastating effects on South Korea's economy, which is already under pressure. To counter this, the South Korean government must engage in tough negotiations with the U.S., utilizing a combination of retaliatory tariffs and investment incentives. Additionally, South Korea should pursue greater trade diversification, strengthening regional trade frameworks like Regional Comprehensive Economic Partnership (RCEP) and the China-Japan-ROK Free Trade Agreement. It's crucial that South Korean firms also take active measures, such as engaging Washington lobbyists and mobilizing their U.S. constituents.

Q: South Korea could face a serious security crisis under Trump's leadership. What are the potential strategies for managing this?

A: While I wouldn't describe it as a crisis, South Korea will undoubtedly face challenging security dynamics. The country has three potential strategies to consider. 1) Compliance: South Korea could acquiesce to American demands, demonstrating continued loyalty to the U.S. conservatives. However, this would not be a popular option among many South Koreans. 2) Protest and defiance: South Korea could resist Trump's demands and engage in tough negotiations. But this may prove difficult, given Trump's dominant and often unilateral negotiating style. 3) Reducing dependence on the U.S.: This is perhaps the most likely strategic option. South Korea could pursue greater self-reliance in defense while improving relations with other countries like North Korea, China and Russia. This would allow South Korea to reduce its security dependence on the U.S., while diversifying its foreign policy approach.

Q: Trump has described North Korea as a nuclear power and suggested a possible summit with Kim Jong-un. How does this stance affect South Korea?

A: Trump's reference to North Korea as a nuclear power has raised concerns in South Korea, which has long adhered to the principle of complete, verifiable and irreversible dismantlement (CVID) of North Korea's nuclear weapons. However, I believe Trump's use of the term "nuclear power" simply reflects his acknowledgment of the reality that North Korea possesses nuclear weapons. It doesn't necessarily imply formal recognition of North Korea as a nuclear weapons state. Trump reaffirmed the denuclearization of North Korea as a common goal when he met Japanese Prime Minister Shigeru Ishiba in Washington, D.C.

In terms of summit diplomacy, Trump seems confident that Kim Jong-un will engage with him again. However, I remain skeptical. North Korea's position is clear: It will not engage diplomatically unless the U.S. abandons its hostile policies, including joint military exercises and training with South Korea, the forward deployment of strategic weapons and the imposition of sanctions. If the two sides can reach a compromise, there is potential for another summit, but only if the U.S. is willing to offer substantial concessions.

Q: Could we see a new bloc structure emerging in Northeast Asia, with Japan, South Korea and the U.S. on one side, and China, North Korea and Russia on the other?

A: I am concerned about the rise of bloc politics in Northeast Asia, which could harken back to the Cold War era. The southern trilateral axis of Japan, South Korea and the U.S. seems solid, but I have doubts about the cohesion of the northern trilateral ties between China, North Korea and Russia.

While Russia and North Korea have strengthened their relationship in the wake of the Russia-Ukraine war, China's ties with North Korea have weakened. China is reluctant to embrace North Korea and Russia in an anti-U.S. front, as it fears a return to a Cold War structure that it sees as an American trap. Moreover, China's concerns about North Korea's actions, particularly in relation to sanctions, suggest that the northern bloc will face significant internal challenges.

Q: What do you think of Trump's claim that he can end the Russia-Ukraine war in 24 hours? How might this impact North Korea-Russia relations and the Korean Peninsula?

A: Trump's promise to end the war in 24 hours was overly optimistic. While it hasn't materialized, there is still a chance for a ceasefire, as the U.S. continues to put pressure on Ukraine and leverage Trump's personal ties with Vladimir Putin.

For North Korea, the war has opened the door for stronger security and economic ties with Russia. North Korea could send troops to support Russia, further cementing their alliance. The new treaty between Kim and Putin, signed in June 2024, demonstrates this growing partnership. North Korea may also seek to gain advanced military technologies from Russia, posing a significant security threat to South Korea. However, there is little evidence that Russia is providing such technology yet, as it remains cautious, preferring to maintain economic ties with Seoul.

Q: In the context of the growing U.S.-China rivalry, what strategic options are available for South Korea?

A: South Korea has several options. One is a pro-American balancing strategy, which is favored by conservatives. Another option is to bandwagon with China, which may appeal to some progressives. A more radical option is for South Korea to stand alone, either by acquiring nuclear weapons or declaring neutrality. These options sound great, but seem unrealistic. Many South Koreans, regardless of conservatives and progressives, favor a "status quo" approach (i.e., alliance with the U.S. and a strategic cooperative partnership with China) that can muddle through the current sandwiched situation. I personally support a transcending diplomacy in which South Korea and like-minded middle powers together engage in a multilateral preventive diplomacy to avoid the coming conflict between China and the U.S.

Q: With South Korea facing external pressures and domestic political turmoil, how should the country navigate these crises?

A: The first priority must be the return of normalcy in domestic politics. Once South Korea achieves stability in its domestic affairs and secures a national consensus, it will be in a better position to handle external challenges with greater ease.

In the age of global uncertainties triggered by Trump 2.0, South Korea should demonstrate diplomatic imagination that can harmonize national interests with values, blend alliance with strategic autonomy and combine bilateralism with multilateralism.