Those two priorities came to a head this week when federal officials said they had arrested 475 “illegal workers” in what they called the largest, single-site Homeland Security enforcement operation ever.

The arrests took place at a $4.3 billion joint venture between South Korean firms Hyundai Motor Group and LG Energy Solution. The plant was set to open next year and supply up to 300,000 lithium ion batteries a year, including some for the adjacent Hyundai plant that makes the Ioniq 5 crossover and three-row Ioniq 9 electric vehicle.

Promoting domestic manufacturing to decrease the nation’s reliance on other countries is a cornerstone of President Donald Trump’s economic agenda. He claims to have secured commitments of nearly $9 trillion in from various companies and countries, including $450 billion from South Korea. He even hosted South Korea’s president Lee Jae-myung at the White House last week, where they discussed the two nations’ partnership.

But building is labor intensive, and many construction workers are immigrants. Of the estimated 11 million people working in the industry, around a quarter were born outside of the U.S., and many are undocumented.

The majority of those arrested at the site in Ellabell, Ga., were South Korean nationals, special agent Steven Schrank told reporters at a news conference Friday. South Korea is working to get its citizens released, The Wall Street Journal reported, citing an official from there.

Many of the people arrested worked for subcontractors, Schrank said. Hyundai said none of the workers were directly employed by them. LG said it would “fully cooperate” with authorities.

No criminal charges have been announced, and the detainees are being held at an Immigration and Customs Enforcement detention center in Folkston, Ga.

“This operation underscores our commitment to protecting jobs for Georgians and Americans, ensuring a level playing field for businesses that comply with the law, safeguarding our economy, and protecting workers from exploitation,” Schrank said.

The raid, dubbed Operation Low Voltage, was part of a wider initiative called Operation Take Back America, which launched on Trump’s inauguration day in January and “marshals the full resources of the Department of Justice to repel the invasion of illegal immigration,” according to a press release.

Immigration advocates called it misguided. “This historic raid may make dramatic headlines, but it does nothing to fix the problems in our broken immigration system: a lack of legal pathways and a misguided focus on punishing workers and families who pose no threat to our communities,” said Michelle Lapointe, legal director at the American Immigration Council in a statement.

President Trump also weighed in on the raid Friday from the Oval Office, saying, “they were illegal aliens,” adding, “ICE was doing its job.”

Write to Anita Hamilton at anita.hamilton@barrons.com