Then-President-elect Donald Trump speaks during a meeting with Republican governors at Mar-a-Lago in Palm Beach, Fla., Jan. 9. AP-Yonhap

Donald Trump's return to the White House is fueling a fierce debate in South Korea, where experts are deliberating whether his administration will demand an increase in defense sharing costs and draw down U.S. Forces Korea (USFK).

Many speculate that Trump's transactional approach to foreign policy and his comments about treating South Korea like a "money machine" will leave Seoul to wonder if it should acquire its own nuclear weapons rather than relying on U.S. extended deterrence.

In December, Trump named Elbridge Colby as the Pentagon's under secretary for defense for policy. Colby has stressed that the U.S. needs to focus more on China and its allies' need to bear greater cost-sharing responsibilities. He also raised fears that the U.S. might withdraw its troops stationed in South Korea.

"Trump has been complaining that too much money is spent on maintaining U.S. troops on the Korean Peninsula and Korea-U.S. joint military exercises, so it is highly likely that he will try to downsize its troops stationed in South Korea and reduce joint military exercises after taking office," Cheong Seong-chang, director of the Center for Korean Peninsula Strategy at the Sejong Institute, said.

However, Cha Du-hyeogn, principal fellow at the Asan Institute for Policy Studies, said it won't be easy for the U.S. to withdraw its troops from South Korea or raise Seoul's share of the costs for stationing the USFK.

"The Trump administration hopes to focus on U.S.-China strategic competition and wants South Korea, Japan and many others to pay more for hosting U.S. troops in their countries. However, it takes considerable time to relocate troops. The USFK also holds strategic value in terms of dealing with potential security challenges from China," Cha said.

"Trump may call for the renegotiation of a recently agreed-upon defense cost-sharing deal between Seoul and Washington, but it's not going to gain much support — not even from Republican senators."

In October last year, South Korea and the U.S. struck the latest five-year deal for the Special Measures Agreement (SMA), outlining that Seoul will pay 1.52 trillion won ($1.04 billion) in 2026, up from 1.4 trillion won in 2025, for hosting 28,500 USFK troops.

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Possibility of Seoul deploying own nuclear weapons

Experts were divided over whether South Korea needs to develop and deploy its own nuclear weapons. The idea of South Korea going nuclear has been gaining traction reflecting a growing distrust in U.S. extended deterrence.

A poll conducted by the East Asia Institute in October showed that 47.4 percent of respondents — up from 26.2 percent a year earlier — disagreed with the notion that the U.S. nuclear umbrella is sufficient to counter North Korea's nuclear threat.

"Public confidence in U.S. extended deterrence is expected to weaken in the foreseeable future. South Korea needs to go nuclear to deter North Korean aggression. If we see a reduction in U.S. forces in Korea or a cutback in joint military exercises, support for nuclear armament here will likely increase further," Cheong said.

Jung Dae-jin, professor of global business at Halla University, said that if the U.S. pursues direct talks with North Korea — an approach that sidesteps participation by South Korea — it may lead to a surge in public support for Seoul going nuclear.

"We need to persuade the U.S. that excluding us from any meaningful negotiations between the U.S. and North Korea may threaten the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) and is ultimately unhelpful to the U.S.," he said during a forum hosted by the Peaceful Unification Advisory Committee, Wednesday.

Weeks ahead of Trump's inauguration, the U.S. reaffirmed its "enduring" and "ironclad" security commitment to South Korea and renewed a warning that any nuclear attack by North Korea against the U.S. and its allies will result in the end of the recalcitrant regime.

Cha said South Korea is far from developing its own nuclear weapons due to political and economic considerations.

"Although we could consider possessing our own nuclear armaments as a last resort, there are plenty of other viable options to deter North Korea's nuclear threats. The Korea-U.S. alliance and U.S. extended deterrence will remain strong under Trump," he said.

Cha explained that South Korea would need to withdraw from the NPT in order to develop its own nuclear weapons, which is not a feasible idea because it would weaken the Seoul-Washington alliance.

"It would severely damage our reputation and relationship with other countries in both economic and security terms. The U.S. would not grant exceptions and would impose sanctions on South Korea," he said.

Cho Chang-rae, right, deputy defense minister for policy, shakes hands with Cara Abercrombie, the U.S. acting deputy under secretary of defense for policy, prior to the fourth session of the Nuclear Consultative Group (NCG) in Washington, Jan. 10. Courtesy of Ministry of National Defense

Vipin Narang, the Frank Stanton professor of nuclear security and political science at the Massachusetts Institute of Technology, said the Nuclear Consultative Group (NCG), launched during the Joe Biden administration, will continue meeting under Trump.

"I personally don't think Trump would support South Korean independent nuclearization," he said during a recent virtual forum hosted by the Institute for Corean-American Studies, a nonprofit research organization.

"I still believe that it's in South Korea's interest to ensconce itself in the extended deterrence umbrella because it's not as if South Korea can get nuclear weapons overnight. There will be a window of vulnerability against a nuclear North Korea that will have an incentive to try and stop South Korea potentially through the use of force."