SEOUL, South Korea (AP) — South Korea’s foreign minister has left for the U.S. to finalize the steps needed for the return of hundreds of South Korean workers detained in a massive immigration raid at a Hyundai plant in Georgia. The incident has caused confusion, shock, and a sense of betrayal among many in South Korea, which is an ally of the U.S.

The raid on September 4 at the battery factory resulted in the detainment of 475 workers, over 300 of whom were South Korean. Video footage showed some workers being shackled, raising serious concerns over the U.S. immigration enforcement methods.

South Korean officials were alerted to the raid just prior to the arrest of their nationals, stirring outrage amongst lawmakers back home. During a legislative session, Foreign Minister Cho Hyun labeled the incident “a very serious matter” that caught his government off guard.

While the South Korean government expressed regret over the situation, experts advise that retaliation is unlikely given the crucial security partnership with the U.S. regarding North Korea and other collaborative efforts.

Cho's visit comes amid a bilateral economic environment where South Korea recently pledged significant investments in the U.S. This fallout raises significant doubts about the U.S. commitment to protect foreign investments despite political changes.

U.S. immigration officials have stated that some detainees entered the U.S. illegally, prompting discussions about America’s tougher stance on immigration and labor policies. As a result, there are fears that businesses may face operational delays and increased labor costs.

With ongoing negotiations on work visas for skilled labor, South Korea hopes to avoid similar incidents in the future as they navigate their investments and diplomatic relations with the United States.