South Korean President Lee Jae Myung ordered all-out efforts on Saturday to respond to the arrests of hundreds of the nation’s citizens in a US immigration raid on a Hyundai Motor car battery factory.

Foreign Minister Cho Hyun said the government has set up a team to respond to Thursday’s arrest of over 300 Koreans at the facility in the southern state of Georgia and that he may go to Washington to meet with officials if needed.

“I am deeply concerned. I feel heavy responsibility for the arrests of our citizens,” Cho told an emergency government meeting.

The arrest of some 475 workers at the plant near Savannah, part of President Donald Trump’s escalating crackdown on immigrants, was the largest single-site enforcement operation in the US Department of Homeland Security’s history.

The incident could exacerbate tensions between the Trump administration and Seoul, a key Asian ally and investor in the US. They have been at odds over the details of a trade deal that includes $350 billion of South Korean investment in the United States.

LG Energy Solution, which is working with Hyundai to build the factory, said it had asked employees to return from US business trips while suspending travel to the United States except for customer meetings.

LG Energy Solution said 47 of its employees and about 250 workers for contractors at the joint venture factory were detained.