South Korea, US Pull Apart as the Alliance Strains

South Korea and the United States are in a tug-of-war over the terms of their alliance. Since March the two governments have clashed over intelligence sharing, investment, and military command. The friction is now visible in small and concrete ways.

The dispute began on March 6 when the South’s Unification Minister Chung Dong-young named the North Korean city of Kusong as the site of a uranium enrichment facility. Washington treated the remark as a disclosure of classified information and has since partially restricted the imagery intelligence shared with Seoul on North Korea. Chung has said he learned of the facility from open sources. Washington did not accept the explanation. In April, National Security Adviser Wi Sung-lac acknowledged that the two governments held different views of the remark.

A second dispute has become entangled with the first. The U.S.-listed e-commerce company Coupang is under investigation in South Korea over a data breach. A July report by the U.S. House Judiciary Committee accused South Korea’s National Intelligence Service of pressuring officials to pursue the company; the NIS called the claim false. In the same April briefing, Wi said the Coupang case concerned a single company. He nonetheless acknowledged that it was affecting security talks and delaying negotiations.

The intelligence service has been affected directly. Washington barred the agency from a June meeting with Japan on North Korean cyber threats and notified Seoul in writing, according to local media reports. The agency called the exclusion a one-time measure. South Korean Ambassador to the U.S. Kang Kyung-hwa also confirmed that visas for two or three agency employees bound for the embassy in Washington had been delayed. The agency attributed the delays to stricter U.S. entry procedures and denied any link to the intelligence dispute. 

Each incident can be explained on its own, but together the impact is mounting on the intelligence relationship. 

Economic pressure has followed a similar course. Seoul hoped that progress on its $350 billion investment pledge under a trade deal with Washington would restart stalled security talks on nuclear-powered submarines and uranium enrichment. However, the specific terms of investment have become a cause of more tension.

U.S. President Donald Trump announced on September 30 that South Korea would invest $54 billion in the Alaska liquefied natural gas project. The trade ministry in Seoul said no decision had been made on whether to invest or how much. Trump pressed the point two days later. On October 2, he warned Seoul of higher costs for staying out of the project. He repeated the investment claim on October 14 in a post on Truth Social.

Before the November 3 midterm elections, Trump has been presenting investment pledges from allies as proof that his tariff policy works. Now Seoul is facing pressure to turn a campaign claim into a financial commitment. The link to security talks gives the dispute weight beyond money.

The strain is also jeopardizing a long-held South Korean military goal. The Lee administration aims to regain wartime operational control (OPCON) of South Korean forces by 2028. U.S. Forces Korea commander General Xavier Brunson – the officer who currently hold wartime OPCON over Korean forces – has cited the first quarter of 2029.

Then, on October 14, Brunson said at a policy forum in Washington that the conditions for the handover had changed. He pointed to recent North Korean missile launches as evidence. He voiced support for the OPCON transfer but opposed rushing it to meet a political deadline. 

South Korean Defense Minister Kang Shin-chul said the next day that Seoul had already conveyed its concerns to Washington. The Defense Ministry maintained that the agreed conditions for the transfer remain unchanged.

On October 19, South Korean President Lee Jae-myung was asked about Brunson’s comments. Speaking at the presidential Blue House, Lee told reporters that Seoul must regain wartime OPCON quickly. He added that talks with Washington are basically moving toward its return. Lee also argued that the process should be called a recovery rather than a transfer. 

A second remark from Brunson drew sharper criticism in Seoul. The Demilitarized Zone is a buffer strip between the two Koreas, and the Military Demarcation Line runs through its middle. At the same forum, Brunson said that South Korea begins at the southern fence of the DMZ from the perspective of the United Nations Command. He commands the U.S.-led United Nations Command, which manages the zone to uphold the armistice. A command official countered that there was no question about South Korean sovereignty.

Lawmakers of the ruling Democratic Party objected. Kim Byung-joo, a special presidential adviser on defense policy, demanded a retraction and an apology. The constitution defines the territory of South Korea as the Korean Peninsula and its adjacent islands. Even read narrowly, the remark did little to reassure a partner seeking more control over its own defense.

This isn’t the first time Brunson had sparked controversy. In May, he had likened South Korea to a “dagger in the heart of Asia,” implying that the U.S. would use military assets stationed on the peninsula to thwart China’s “ambitions beyond that.” Seoul has conveyed its concerns about Brunson through several channels and reportedly received a sympathetic reply from the U.S. side.

The latest frictions in South Korea-U.S. relations came as North Korea stepped up its weapons tests. On October 15, North Korean state media reported that the country had tested two types of submarine-launched strategic cruise missiles the day before. That followed a launch of tactical ballistic missiles on October 12. 

A land mine explosion wounded three South Korean soldiers in the DMZ on September 21. The South Korean Joint Chiefs of Staff have determined that North Korea planted the mines.

On October 19, Kim Yo Jong, the powerful sister of North Korean leader Kim Jong Un, said in a statement that South Korean troops had fired warning shots at North Korean personnel working on border fortifications. She accused South Korean forces of carrying out 2,870 loudspeaker warnings and 201 warning shots between August 1 and October 17. 

Kim added that the North Korean military was considering deploying more tactical strike weapons along the southern border and resuming loudspeaker broadcasts against the South. She also accused the Lee administration of escalating confrontation faster than his conservative predecessor, Yoon Suk-yeol.

On one level, the alliance is still robust. Communication continues between South Korea and the U.S. as usual. But behind the facade of normal interactions, analysts worry that Seoul is increasingly facing steep costs for saying no to U.S. demands. Across intelligence, trade, and military command, Washington is interlinking issues so that Seoul faces restrictions and threats on all fronts. That looks more like a transactional relationship than the “ironclad” alliance the two foreign ministers reaffirmed on September 18. 

A partner that can only follow is not an ally in the full sense of the word.