President-elect Donald Trump is expected to reorient America's approach to the alliance with South Korea, North Korea's nuclear quandary, trade and other key policy issues, experts said, as he is poised to put his "America First" credo front and center.

Trump's second-term administration would return to a diplomatic playbook that could put pressure on US allies to jack up their defense spending and take greater security responsibilities, and curtail the United States' costly overseas involvement, they said.

His policy approach will take concrete shape following a policy review and the formation of his security and foreign affairs team at a time when the world is beset by a grab bag of major geopolitical and security challenges, including North Korea's nuclear threats, China's maritime assertiveness, Russia's war in Ukraine and instability in the Middle East.

US allies and partners have already set in motion efforts to navigate looming uncertainties stemming from what could be an unconventional brand of Trump's diplomacy that focuses on the transactional nature of state-to-state relations.

In particular, South Korea has been trying to figure out what Trump's second term would mean for the US' nuclear deterrence pledge, its diplomacy with a provocative North Korea, the presence of the 28,500-strong US Forces Korea (USFK) and bilateral trade to name a few.

Andrew Yeo, the SK-Korea Foundation chair at the Brookings Institution's Center for East Asia Policy Studies, said that the road for South Korea-US relations may be "more bumpy and unpredictable" under Trump for several reasons.

Among the reasons, the scholar pointed out Trump's desire to see South Korea increase its financial contributions for the stationing of USFK.

In an interview with Bloomberg News last month, Trump said if he were in the White House, South Korea would be paying US$10 billion per year to help maintain the USFK personnel. He also portrayed South Korea as a "money machine."

Trump's remarks came less than two weeks after Seoul and Washington struck a defense cost-sharing deal in early October. Under the deal for the 2026-2030 period, Seoul is to pay 1.52 trillion won (US$1.10 billion) in 2026, up from 1.4 trillion won in 2025.

"Trump has stated repeatedly that he would charge South Korea more for US troops deployed to South Korea, which could cause friction with Seoul," Yeo said.

The president-elect also suggested in a Time magazine interview in April that the US could pull out its forces if South Korea does not pay more to support USFK.

On North Korea, expectations have persisted that Trump could revive his direct diplomacy with North Korean leader Kim Jong-un. Some observers pin hopes on the possibility that Trump could create a rare diplomatic opening to encourage Pyongyang's return to dialogue.

On the campaign trail, he has repeatedly boasted about his "love letters" and personal ties with Kim, even anticipating that the reclusive leader might like to see him return to office.

"I got along with him, and we stopped the missile launches from North Korea. Now, North Korea is acting up again, but when we get back, I get along with him," he said during a speech to accept the GOP presidential nomination in July.

"He'd like to see me back too. I think he misses me," he added, noting that it is "nice to get along with somebody who has a lot of nuclear weapons."

During his time in office, Trump employed a direct leader-to-leader approach to the North, leading to three in-person meetings with Kim, including the first-ever bilateral summit in Singapore in 2018, though serious nuclear talks have been stalled since the no-deal summit in Hanoi in February 2019.

At the Hanoi summit, the North Korean leader offered to dismantle the mainstay Yongbyon nuclear complex, but Trump apparently wanted more concessions as the US saw the complex as only a part of the North's sprawling nuclear program.

"Trump has an affinity for strongmen like Kim and Putin. Trump mentioned he gets along well with Kim. Although this view is not shared by traditional Republicans, or those in the US national security establishment, this perception may affect his decision-making on North Korea policy," Yeo said.

"In particular, if Kim or Putin decide to reach out to Trump to strike a deal on Ukraine or on risk mitigation, Trump may offer concessions without consulting allies and undermine regional security for allies like South Korea," he added.

It remains uncertain whether North Korea would accede to diplomatic feelers from Washington.

Observers believe that Pyongyang's appetite for reengagement with Washington might have dwindled as it has bolstered ties with Russia and maintained its long-standing friendly partnership with China.

Even if nuclear negotiations with North Korea resume, bargaining could be much tougher than before given that Pyongyang has apparently made much headway in its efforts to improve nuclear warheads and delivery vehicles, including intercontinental ballistic missiles.

But many anticipate that Trump might be eager to put a coda -- befitting his "deal-making" finesse -- to the unfinished business of addressing the North's nuclear conundrum.

"Trump has made a big deal of his ability to negotiate with Kim Jong-un. But Kim was furious with Trump after the Hanoi summit in 2019," Bruce Bennett, a senior analyst at the RAND Corp., told Yonhap News Agency via email. "It is not at all clear that Kim will agree to meet with Trump unless Trump offers Kim some major concessions."

Whether bilateral and trilateral security cooperation would continue under Trump remains to be seen.

If the past is any guide, Trump is not fond of institutional frameworks. During his first term, his foreign policy stance was seen as an "isolationist" approach that saw the US withdraw from various global institutions, including the Paris Climate Agreement, the then Trans-Pacific Partnership and UNESCO.

But some observers said that given the cost effectiveness of leveraging alliances in tackling security challenges, Trump could retain such cooperative partnerships.

After all, Trump's security policy will be informed and guided partially by a newly minted team of his advisers, analysts said.

"While many people assume that policies Trump has advocated in the past will be what he does in the future, I think it is entirely possible that Trump will reevaluate a number of things he has said in the past," Bennett said.

"But that will depend upon who his senior appointees are for national security, including the secretary of defense, the secretary of state and the national security adviser."

Yeo echoed the view.

"A lot of what happens under Trump may be determined by who Trump chooses to surround him in his cabinet. If conservative, mainstream Republicans with hawkish views towards illiberal regimes have Trump's ear, a Trump administration would likely lean on the US-ROK alliance to maintain regional security," he said, referring to South Korea by its official name, the Republic of Korea.

"If he's surrounded by MAGA-wing Republicans who want to disengage from global affairs, we will see a major shift away from liberal engagement with allies and partners."

On the trade front, Trump's pursuit of tariffs on foreign goods is expected to be a source of concern.

Trump has said he might slap tariffs of up to 20 percent on all US imports while proposing a 60 percent tariff on Chinese goods.

He has also been pursuing what he calls the "manufacturing renaissance" under his "new American industrialism." His policy proposals could affect South Korean firms doing business with America.

"You will see a mass exodus of manufacturing from China to Pennsylvania, from Korea to North Carolina, from Germany to right here in Georgia," Trump said in a campaign speech in September. "They're going to come to Georgia from Germany and other places." ( Yonhap)