300 South Koreans detained by ICE in Georgia wait for their flight home

More than 300 South Korean nationals detained by federal agents in a massive immigration raid last week on a Hyundai plant in Georgia for alleged visa violations were waiting Wednesday for a charter flight due to carry them back to their country.

The South Korean workers were among some 475 people detained on Sept. 4 by Immigration and Customs Enforcement agents at a still-under construction joint Hyundai-LG electric vehicle battery facility near Savannah. ICE said they were suspected of living and working in the U.S. illegally.

South Korea's Ministry of Foreign Affairs said the departure of the Air Korea charter flight, which had been expected on Wednesday, was delayed due to unspecified circumstances in the U.S., but it would not provide any further information.

A spokesperson for Hartsfield-Jackson airport in Atlanta told CBS News that the charter operation to transport the detainees had been canceled for Wednesday, subject to change. The spokesperson did not provide any information on the reason for the change in plans.

The raid and the detention of hundreds of South Koreans in an ICE facility has tested U.S.-South Korea ties that are important politically, militarily and economically. South Korea is the biggest foreign direct investor in the U.S. and the sixth biggest trading partner overall.

President Lee Jae Myung, visiting the White House in July, pledged $350 billion in new U.S. investment to sweeten a trade-and-tariff deal with President Trump.

"The sentiment is obviously very, very negative," James Kim, Chairman and CEO of the American Chamber of Commerce in Seoul, told CBS News. "In my office, I usually have my TV turned on to the news - and this is obviously covered from morning to evening constantly. But everyone who I speak to, they view America as its number-one partner here from South Korea. Yes, we're going to have some challenging times."

South Korean Foreign Minister Cho Hyun, was peppered with demands from angry lawmakers during a parliamentary session in Seoul on Sept. 8, before he departed for meetings with Secretary of State Marco Rubio and other U.S. officials.

Lawmaker Kim Joon-hyun demanded that Cho respond to the ICE raid by launching investigations into every U.S. national teaching English in South Korea who could be working illegally on a tourist visa.

"Are we giving our money, technology, and investment to the United States only to be treated like this?," Kim asked.

Cho replied by saying he would try to negotiate with Rubio to increase the number of visas issued to highly skilled Korean nationals to work in specialty occupations in the U.S.

The U.S. Department of Homeland Security said the ICE raid was the biggest single-site enforcement action in the agency's history. ICE alleges that the South Korean workers either overstayed their visa waiver permits, known as ESTAs, which allow business visits of up to 90 days, or were holding visas that did not permit them to perform manual labor, called B-1 business visas.

Kim, at the American Chamber in Seoul, called it a "blip" in U.S.-Korea ties and said he was "very, very optimistic about a much brighter future between the two" countries.

South Korea's president, however, took a more critical tone.

"As the president who is in charge of national safety, I feel a great responsibility," Lee said Tuesday. "I hope that the unfair infringement of our people and corporate activities for the joint development of both Korea and the United States will not happen again."

A poll conducted in South Korea found that almost 60% of respondents said they were disappointed by the U.S. crackdown and called the measures "excessive," while about 31% said the ICE action was "inevitable" and that they could understand the reasoning.

President Trump, in a Sunday post on his Truth Social platform, addressed all foreign companies operating in the U.S., saying "your investments are welcome, and we encourage you to LEGALLY bring your very smart people."

Kim at the chamber of commerce urged companies to heed the advice.

"My key message is listen to what President Trump said today. He wants to encourage more foreign companies to invest in America. Bring your people, bring your resources into America, but do it legally," he told CBS News.

Industry experts caution, however, that it may be difficult to maintain investment levels under those guidelines, as securing visas can take years, while many projects face strict deadlines and delays can drive up costs. There is a shortage of highly skilled workers in the U.S., meanwhile, for battery manufacturing, semiconductor and modern shipbuilding industries — all arenas in which South Korea has been investing heavily for years.

Such jobs can require years of experience, not just a few months of on-the-job training.

A spokesperson for South Korea's Foreign Ministry told CBS News that since Mr. Trump's second term began, it had already reached out 52 times on the matter of securing more visas for highly-skilled workers.

Kim, the U.S. chamber of commerce leader, said the current upset in relations represented "an opportunity to really fix some things that could be in the grey area, make it a lot more clear, so that they can have an even better relationship."

He said that, given Seoul's importance as an investor in the U.S., it may be a good time for Washington to consider adopting a new policy that allows South Koreans to more easily come and work in the U.S.

"I think that in the past, Korea may not have been a significant investor in the United States, but now they are," he said. "So I think it's worthy and deserving of that kind of a new status."

Mr. Trump gave a nod in his Truth Social post to the notion that the U.S. does need foreign expertise, saying foreign companies should bring people over to help train American workers — and then hire them to do the work themselves.

Rubio, during his meeting Wednesday in Washington with South Korean Foreign Minister Cho, "said the United States welcomes ROK (South Korea) investment into the United States and stated his interest in deepening cooperation on this front," according to a readout shared by the State Department, which did not mention the ICE raid in Georgia.

Rubio and Cho discussed advancing U.S.-South Korean ties "through a forward-looking agenda" that "revitalizes American manufacturing through ROK investment in shipbuilding and other strategic sectors, and promotes a fair and reciprocal trade partnership," the State Department said.

Skyler Henry contributed to this report.