South Korean Foreign Minister Cho Hyun is set to travel to the United States on Monday as the fallout continues from an immigration raid on a Hyundai plant in Georgia during which over 300 South Korean workers were detained. On Sunday, the South Korean government said it had finalized negotiations for the workers' release and planned to send a charter plane to bring them back to Seoul. But the incident risks seriously damaging relations between the United States and South Korea at a time when Seoul has committed to massive investment plans in America. Hyundai raid strains US-South Korean relations Wednesday's raid on the sprawling Hyundai-LG electric vehicle battery factory under construction in Georgia came just ten days after South Korea's new center-left president, Lee Jae Myung, met with US President Donald Trump in Washington, where the two pledged closer business ties. As recently as July, South Korea agreed to purchase $100 billion (around €85 billion) in US energy and make a $350 billion investment in the US in return for lower tariff rates. "Launching a massive crackdown while urging 'investment' — is this how you treat an ally?" headlined South Korea's left-leaning Hankyoreh newspaper on Monday, adding: "This incident has left the Korean people feeling betrayed." Hundreds arrested in US immigration raid on Hyundai plant 01:50 Georgia: Why did ICE raid Hyundai plant? Video footage released by US Immigration and Customs Enforcement (ICE) on Saturday showed a column of vehicles approaching the site in Georgia and then federal agents directing workers to line up outside. Some detainees were ordered to put their hands up against a bus as they were patted down before having their hands, ankles and waists cuffed. Steven Schrank, Homeland Security Investigations lead for Georgia, told a news conference that some of the detained workers had illegally crossed the US border. Others, he claimed, had entered the country legally but had expired visas, or had entered on a visa waiver that prohibited them from working. "It's almost certain they were there on ESTA or B-1 visas, which permit only business meetings, not construction activities," US-licensed attorney Yum Seung-yul told news agency AFP. None have been officially charged with any crimes, said Schrank, adding that investigations were ongoing — before the announcement on Sunday that the South Korean government would fly the workers home. Kang Hoon-sik, chief of staff for President Lee Jae Myung, said that Seoul will push to review and improve visa systems for those traveling to the US on business trips or for investment projects.