Jitters increase about future of South Korea-U.S. alliance

SEOUL, South Korea — Foreign relations experts worry that the leaders in Seoul and Washington could do what no enemy has managed in 75 years: fray the two democracies’ alliance to the breaking point.

On Friday, top diplomats from Seoul, Tokyo and Washington huddled in Southeast Asia. In Northeast Asia, warplanes from the three nations drilled together in the clouds over a strategic island while generals talked regional deterrence.

Those cheery photo ops and upbeat military vibes, however, may not allay deeper fears.

In Washington, concerns are simmering that South Korea’s newly elected liberal president, Lee Jae-myung, could degrade the bilateral alliance.

In Seoul, those sentiments are mirrored in fears that President Trump’s intermingling of commercial and strategic issues could hurt the relationship, specifically if he links his promised tariffs with the U.S. military presence.

Diplomats chat, warplanes thunder

Top diplomats from the U.S., South Korea and Japan met for 40 minutes in Kuala Lumpur, Malaysia, on the sidelines of the Association of Southeast Asian Nations summit.

Although none of their countries is an ASEAN member, Secretary of State Marco Rubio, Japanese Foreign Minister Takeshi Iwaya and South Korean Vice Foreign Minister Park Yoon-joo attended the meeting. Mr. Park, who was deployed as the foreign minister-appointee of the Lee administration, is undergoing hearings.

The trio affirmed their resolute commitment to North Korean denuclearization, per Korean media.

In Seoul, meanwhile, the top military brass of all three nations held their annual meeting.

“We’re illuminating a future path together, a path where partnerships can evolve through persistent and regular engagement from building capacity to really sharing responsibility,” Gen. Dan Caine, chairman of the Joint Chiefs of Staff, told his counterparts. He noted that North Korea and China were “undergoing an unprecedented military buildup with a clear and unambiguous intent to move forward with their own agendas.”

South Korean and Japanese jets drilled with a U.S. B-52 strategic bomber in international airspace close to South Korea’s Jeju Island.

The holiday isle has a near-perfect strategic location south of the peninsula and northeast of Shanghai at the convergence of the Yellow and East China seas.

Chinese naval bases, naval shipyards and one of Beijing’s three fleet commands lie on the Yellow Sea littoral. Any North Korean warship seeking to cross from the peninsula’s east coast to its west coast, or vice versa, must traverse the area.

Jeju’s naval base offers South Korean and visiting U.S. assets an ideal staging point for regional operations inside the First Island Chain.

Despite Friday’s amicable gatherings, pundits fret over the relationship.

New pragmatist or old leftist?

Some pundits consider Mr. Lee, who took power last month after conservative President Yoon Suk Yeol’s impeachment, an unreformed radical.

Formerly known to despise Japan and favor better ties with China and North Korea, Mr. Lee pivoted once the Blue House came within reach.

He rebranded his liberal Democratic Party of Korea as “center-right” and talked of “pragmatic” politics. He vowed to maintain Seoul’s alliance with the U.S. and its emergent trilateral ties with Japan, long desired by the U.S. and championed by Mr. Yoon.

So far, he has kept his word.

His first major diplomatic engagement was with Japanese Prime Minister Shigeru Ishiba at the June Group of Seven summit in Canada. That went so well that Mr. Ishiba visited the South Korean Embassy in Tokyo days later to celebrate six decades of diplomatic ties.

Mr. Lee’s national security adviser, visiting Washington last week, urged Mr. Rubio to set up a Lee-Trump meeting.

None of that has stopped U.S. conservatives from issuing dire warnings.

In a June op-ed in The Hill, conservative pundit Gordon Chang wrote that Mr. Lee “almost certainly wants American troops off South Korean soil.” He cited comments earlier in Mr. Lee’s career that they are “an occupying force.”

He warned that Mr. Lee may govern as “an anti-American, pro-China, pro-North Korea leftist.”

Any South Korean president seeking to end the U.S. alliance faces an uphill battle. A 2025 poll by Seoul’s Asan Institute found that 96% of Koreans consider the alliance necessary, and support for GIs in South Korea stood at 80.1%.

“The whole development of South Korea was made possible under the umbrella provided by the U.S.,” said Michael Breen, the Seoul-based author of “The New Koreans.” “Neither side of the political aisle since Korea became a democracy has wanted to change that.”

From 2017 to 2022, the liberal South Korean government of President Moon Jae-in dragged relations with Tokyo to all-time lows. Though Mr. Moon held summits with North Korea’s leader more often than any prior South Korean president, he neither broke sanctions against Pyongyang nor ended the U.S. alliance.

“Some elements in Lee’s party are anti-U.S., but they are fringe. … He will be as pragmatic as possible,” predicted Jeffrey Robertson, an international relations expert at Seoul’s Yonsei University. “Like all former progressive presidents, he will stick to the center line.”

Trump’s Korea strategy

Some fear the latest news out of Washington.

“It depends on who Trump is listening to in the U.S.,” Mr. Robertson said. “If he gets the idea that Lee is anti-U.S. … that is illegitimate.”

Potential cuts to U.S. Forces Korea, or “flexible” use of the forces for off-peninsula roles, could be in play. In a Cabinet meeting last week, Mr. Trump raised the issue of South Korea paying more for GIs stationed there.

More disturbing for some is Mr. Trump’s habit of packaging together separate issues.

“Trump is tying trade and security together, and I don’t agree with that. I think they should be separate,” said Chun In-bum, a retired South Korean general. “He is describing USFK as a bargaining chip, and that is really disturbing.”

The ploy, he said, could blow back by playing to Seoul’s hard left.

“As some Korean progressives don’t see North Korea as a security threat, they may accept a trade-off, U.S. troop cuts for tariffs, which is ridiculous,” Gen. Chun said.

Mr. Trump said last week that he would levy 25% tariffs on South Korea starting Aug. 1 if a trade deal between the two countries isn’t reached.

Other Koreans fear tariffs could reignite mass anti-Americanism, dormant in South Korea since the 2008 protests over U.S. beef imports.

“If Trump wages tariff war against South Korea, threatens to withdraw U.S. forces and demands increased defense spending and burden sharing, I think the majority of South Koreans will be critical of him and the U.S.,” said a Seoul-based academic with ties to the Lee government.

Minefields also lie ahead in the diplomatic space.

“Lee has made it clear he wants to keep the alliance and honor trilateral relations,” said the academic, who spoke off the record because he did not want to be considered an administration spokesperson. “However, he also wants a cooperative partnership with China and better diplomatic ties with Russia.”