United States President-elect Donald Trump delivers a speech from the Palm Beach Convention Center at the Trump Campaign Election Night Watch Party in West Palm Beach, Florida, Wednesday (local time). UPI-Yonhap

South Korea needs to move away from relying too much on its alliance with the U.S. and rethink its foreign and security policy as U.S. President-elect Donald Trump is expected to pursue a more aggressive version of his "America First" policy following a decisive victory, experts said.

Some say that Trump has completely changed the course of U.S. politics over the last decade, making South Korea wonder if its alliance with the U.S. will be resilient enough to withstand another four years of the "America First" approach.

"The days when South Korea could rely solely on its alliance with the U.S. are over. Trump may push for a more 'transactional' approach in his second term. He will also likely infuse economic nationalism into his administration," Lee Hea-jeong, professor of political science at Chung-Ang University, said at a seminar at the National Assembly on Thursday, a day after Trump won the U.S. presidential election.

"Under such circumstances, South Korea needs to do some soul-searching, seek common ground with the U.S. and establish itself as a significant actor on the Korean Peninsula."

Experts participating in the seminar said that Trump is likely to call for the renegotiation of a recently agreed-upon defense cost-sharing deal between Seoul and Washington. During his campaign, Trump called South Korea a "money machine" in an attempt to put pressure on Seoul to raise its share of defense spending for the stationing of U.S. Forces Korea. He had even threatened to withdraw U.S. troops from South Korea unless Seoul increased its contribution.

"Trump is not the type of president who has a grand strategy. His foreign policy approach is mainly about slapping steep tariffs and demanding a raise in allies' defense cost-sharing. Trump mentioned withdrawing U.S. troops from South Korea, but that is to leverage its negotiating position on defense cost-sharing," Seo Jung-kun, professor of political science at Kyung Hee University, said.

Seo called on the Assembly to speed up the ratification procedure to gain an upper hand in potential renegotiation.

In October, South Korea and the U.S. finalized the 12th Special Measures Agreement outlining Seoul's financial obligations for hosting 28,500 American troops. Under this agreement, South Korea will contribute 1.52 trillion won ($1.1 billion) in 2026, marking an 8.3 percent increase from 2025.

"Our parliament must hurry up and ratify the defense cost-sharing agreement between Seoul and Washington. We need to take a more structural approach in building diplomatic relationships with Trump's aides who can help moderate him," Seo said.

Yang Moo-jin, president of the University of North Korean Studies, said the South Korea-U.S. alliance and the trilateral security cooperation between South Korea, the U.S. and Japan will undergo changes.

"The Trump administration would probably pressure South Korea to increase defense spending, scale back joint military exercises and reduce deployment of its strategic assets," Yang said. "Trump might want to realign the trilateral cooperation as it is the Joe Biden administration's achievement, but may leave it as it is if he thinks it's effective in countering China."

Then-U.S. President Donald Trump meets with North Korean leader Kim Jong-un at the demilitarized zone separating the two Koreas, in Panmunjeom, South Korea, June 30, 2019. Reuters-Yonhap

Potential summit with NK leader

Experts agreed that Trump would revive direct diplomacy with North Korea to shape his own legacy.

"Trump might want to hold another summit with Kim Jong-un sometime between the U.S. midterm election in 2026 and the next U.S. presidential election in 2028. He would still want to be at the center of attention. However, the North Korean leader should consider how much he can gain from a president with a four-year term," Seo said.

Yang echoed this view, saying, "Trump is expected to revive personal diplomacy with Kim Jong-un and pursue a top-down style — first holding a leader-to-leader summit and then organizing working-level talks. North Korea might focus on pressuring the U.S. to accept it as a nuclear state and asking for sanctions relief in return."

However, experts were divided on whether North Korea is in the U.S.' top foreign policy priorities.

"I don't think the U.S. is shifting its focus away from North Korea. The U.S. doesn't have a solution to the North Korean issue, that's all. I think traditional media and social media's roles are important in shaping public perception of North Korea. It is not covered in the U.S. media as much as the Ukraine war or Israel-Hamas war," Seo said.

On the other hand, Yang said, "North Korea may remain lower on the list of U.S. foreign policy priorities considering the two wars (in Ukraine and the Middle East) and competition with China."