475 Detained at Hyundai‑LG $4.3B Battery Site - Seoul Presses U.S. to Re‑admit About 300 Korean Workers

Seoul is pressing Washington to let a group of South Korean workers arrested in a dramatic U.S. immigration sweep return to the United States, after raids at a major battery plant project rattled both sides of the Pacific.

Foreign Minister Cho Hyun left for Washington to raise the matter directly with U.S. Secretary of State Marco Rubio. Seoul wants the roughly 300 South Koreans who were among 475 people detained at the sprawling battery site to be allowed back into the U.S. after they are flown home, officials said. The detainees are expected to be returned on a charter flight labelled a "voluntary departure." Cho told lawmakers that Seoul negotiated on the basis that the workers would face no lasting personal penalties.

The enforcement action took place at the site of a $4.3 billion battery facility being built by Hyundai Motor (KRX: 005380) and LG Energy Solution (KRX: 373220). It was the largest single-site operation in the Department of Homeland Security's investigative history, and video of armoured vehicles and shackled workers provoked strong reaction back in Seoul.

Details about how the workers allegedly violated U.S. immigration rules remain thin. South Korean lawmakers suggested some people may have gone beyond what a 90-day visa waiver or a B-1 business visa allows - for example, working on a test run of the factory ahead of the planned October production start. Seoul has argued many of the detained were subcontractor staff or technical specialists sent because companies were having trouble finding qualified U.S. workers.

Corporate fallout was immediate. A Hyundai Motor spokesperson said none of the detained were direct employees and that vehicle production at the site wasn't affected. Still, the automaker has asked staff to pause non-essential travel to the United States. LG Energy Solution (KRX: 373220) has halted most business trips and is recalling employees based in South Korea who are already in the U.S.; construction at the plant was paused as the company cooperates with authorities.

Politically, the timing is awkward. The raid came about ten days after President Lee Jae Myung met with President Donald Trump in Washington, where both sides touted closer business ties. South Korea is also in the middle of lining up large U.S. investments-Seoul-backed pledges run into the hundreds of billions-so the episode has the potential to complicate diplomatic and commercial discussions.

Washington's public line was blunt: Trump said he hadn't known about the specific raid and called those detained "illegal aliens," while also telling foreign firms their investments are welcome so long as entrance is legal and orderly. That mix of firmness and a promise to make legal routes faster has left an opening for diplomacy: Cho plans to press for a more streamlined visa process for Korean technical teams moving forward.

For markets, the immediate variables are clear. The detentions stirred noise around the two principal corporate names tied to the project. Construction delays, heightened compliance scrutiny, and suspended staff movements add operational uncertainty. On the flip side, large-scale foreign direct investment commitments and the strategic importance of EV battery capacity make this more of a diplomatic headache than an existential business threat-at least for now.

Whether Washington will carve out faster, clearer channels for foreign technical teams without triggering tighter enforcement is the next question. Cho's trip wraps up midweek; the detained workers' charter flight is expected to leave soon. The headline numbers: 475 people detained at a $4.3 billion project, with roughly 300 of them South Korean nationals.

Which way this plays out could shape hiring practices, contractor oversight and how global manufacturers staff U.S. build-outs going forward. Will the episode lead to smoother visa lanes or to more cautious overseas staffing? Time will tell.