In his post, Trump said that foreign investment in the US remained welcome, stressing that companies could “LEGALLY bring (their) very smart people, with great technical talent, to build World Class products.” He added that his administration would ensure the process was handled “quickly and legally.”

Urging firms to hire and train American workers, he wrote: “What we ask in return is that you hire and train American Workers. Together, we will all work hard to make our Nation not only productive, but closer in unity than ever before.”

Speaking to reporters at Andrews Air Force Base, Trump suggested the US could temporarily allow foreign experts to help train American workers in specialist industries such as battery manufacturing. “The way you train people is bring people in that know what they’re doing, let them stay for a little while and help,” he said, according to AP.

Hundreds detained in Georgia

On Thursday, federal agents arrested about 475 workers at Hyundai’s car battery plant in Ellabell, Georgia, making it the largest single-site immigration enforcement operation in the history of the Department of Homeland Security’s investigative arm, Reuters reported.

Workers await shackling during the immigration raid at Hyundai’s EV plant in Ellabell, Georgia, Sept 4. (Photo: US Immigration and Customs Enforcement via AP)

Most of those detained were South Korean nationals, with Seoul confirming that more than 300 of its citizens were among them. Officials said some workers had crossed the border illegally, while others had overstayed visas or entered under visa waivers that did not permit employment.

Video released by US Immigration and Customs Enforcement showed agents arriving in convoys, ordering workers to line up, and shackling some detainees before transferring them to a detention facility in Folkston, near the Florida border.

South Korea to repatriate workers

South Korea said it had reached agreement with Washington for the workers’ release. Kang Hoon-sik, chief of staff to President Lee Jae Myung, announced that a charter plane would be sent once administrative steps were finalised.

Foreign Minister Cho Hyun is also due to travel to the US for talks on the matter.

According to South Korean media cited by Reutersthe workers could return as early as Wednesday. Seoul’s Foreign Ministry expressed “concern and regret” over the incident and said it would examine visa arrangements to prevent similar problems in future, reported AP.

The raid has caused dismay in South Korea, a key US ally and investor, as it came less than two weeks after Trump and Lee pledged closer business cooperation during their first summit in Washington.

South Korea recently agreed to purchase $100 billion worth of US energy and invest $350 billion in the country in exchange for tariff concessions. Hyundai has also committed $26 billion to its US operations, including the Georgia plant targeted in the raid, which is a $4.3 billion joint venture with LG Energy Solution.

(With inputs from AP, Reuters)