Behind the shocking sight of hundreds of South Korean workers being chained and detained at a Georgia battery factory is the Trump administration’s other target: companies that hire illegal workers.

While President Donald Trump has launched sweeping immigration raids on a promise to deliver the largest mass deportation in history, administration officials are also taking a harder line against employers they say cheat American workers by hiring undocumented immigrants.

Since 1986, employers have been required to verify workers’ eligibility to work, and can be fined or jailed if caught knowingly breaking the law. But enforcement has typically focused on the workers, not those who hire them.

Because company owners and managers have rarely been prosecuted or penalized, Trump officials say some employers are too willing to exploit desperate workers through lower pay and dangerous working conditions – and then pocket the savings. Some employers argue there aren’t enough willing American workers to do the toughest jobs, at the wages they’re offering.

Since January, the Trump administration has targeted workers at raids of California car washes and marijuana farms, a Louisiana racetrack, a Florida construction site and a Nebraska meatpacking plant. And while those enforcement actions have not yet translated into criminal cases or fines against the employers, the raids themselves in some cases significantly disrupted business operations.

But the administration has also fined two Colorado cleaning companies millions of dollars for hiring dozens of undocumented workers and won criminal indictments in two other schemes to employ illegal labor in Arizona and Ohio.

Officials declined to comment on what they said is an active criminal investigation at the Georgia plant, sparked in part by local labor unions’ complaints that foreign workers were filling jobs.

Raid at a factory making batteries for Hyundai

The new push complicates the president’s efforts to rebuild American manufacturing, given the potential chilling effect it could have on foreign companies being pushed to expand in the United States, amid ongoing labor shortages in many industries.

Citing a monthslong criminal workplace investigation, federal officials on Sept. 4 raided the HL-GA Battery Company project about 30 miles northwest of Savannah, detaining nearly 500 workers. The majority of the detained employees were South Koreans who lacked permission to work in the United States.

“We welcome all companies who want to invest in the U.S., and if they need to bring workers in for building or other projects, that’s fine ‒ but they need to do it the legal way,” Special Agent in Charge Steven Schrank of Homeland Security Investigations in Georgia and Alabama said in news conference following the raid. “This operation sends a clear message that those who exploit the system and undermine our workforce will be held accountable.”

So far, only the detained workers are facing punishment: They were whisked off to immigration detention sites for deportation. South Korean officials say they’re working with the U.S. State Department to voluntarily repatriate the approximately 300 detained South Korean citizens. South Korean media reported the workers could fly home via charter flight as soon as Sept. 10.

The South Korean workers’ treatment stands in stark contrast to the experiences of tens of thousands of Mexicans, Venezuelans and Guatemalans who face months in jail-like detention centers before being forcibly deported.

The raid also stands out because worksite enforcement actions have been rare in recent years. HSI records show investigations into employers can take years to bring to trial, although the Trump administration has recently injected new urgency into those cases, issuing millions of dollars in fines and bringing criminal cases against employers across the country.

Over the past decade, there have been fewer than 200 federal prosecutions of employers for hiring illegal labor, according to researcher Brian Owsley, associate professor of law at the University of North Texas-Dallas College of Law, who follows worksite immigration enforcement. The Biden administration largely halted raids on employers, he said.

Manufacturing experts say the U.S. workforce lacks some of the technical expertise that South Korean and other international workers have; and their specialized knowledge is required to ramp up production in this country. The battery plant will serve the adjacent Hyundai Metaplant car factory. The projects received millions in state and local tax incentives after promising to create thousands of new jobs.

Federal officials say they’re closely watching workplaces

Federal investigators say the raid was the result of a monthslong investigation into employment practices at the site, but court documents show no evidence they knew there were large numbers of South Koreans working there. Instead, the only four people listed as specific targets in the search warrant have Hispanic names.

The Department of Homeland Security and ICE didn’t immediately respond to a request for comment regarding the specifics of the search warrant or the four “target persons” listed.

In a Sept. 7 social media statement, Trump acknowledged that his immigration crackdown complicated his goals of bringing back manufacturing. Since January, the White House has touted hundreds of billions of dollars in commitments from foreign companies like Hyundai, which co-owns the plant with LG.

“I am hereby calling on all foreign companies investing in the United States to please respect our nation’s immigration laws,” Trump said. “Your investments are welcome, and we encourage you to LEGALLY bring your very smart people, with great technical talent, to build world-class products, and we will make it quickly and legally possible for you to do so. What we ask in return is that you hire and train American workers.”

Border czar Tom Homan struck a more combative tone, warning employers that federal officials are closely watching workplaces. Federal officials have already raided, among others, California car washes and marijuana farms, a Louisiana racetrack, a Florida construction site and a Nebraska meatpacking plant.

“We’re going to do more worksite enforcement operations,” Homan told CNN. “No one hires an illegal alien out of the goodness of their heart. They hire them because they can work them harder, pay them less, undercut the competition that hires U.S. citizen employees.”

Employers rarely prosecuted for hiring undocumented

The American Immigration Council estimates that at least 6% of manufacturing workers nationwide are undocumented, according to an analysis of U.S. census data. They represent 7% of the manufacturing workforce in Georgia.

Employers rarely get prosecuted for hiring illegal workers: Although federal law provides for $3,000 fines and up to six months in jail, it’s only enforced when federal officials decide an employer has committed a “pattern or practice” of routinely hiring employees who are not legally allowed to work in the United States.

In other words, while it’s a felony for a worker to provide false papers, the employer has little incentive to closely scrutinize that paperwork. Instead, they can plead ignorance and almost always avoid punishment.

The federal E-Verify system is supposed to help employers ascertain whether a job applicant has work authorization, but it’s up to states to determine whether to require its use. Fewer than half of states mandate the use of E-Verify for public and some private employers, according to a World Population Review analysis.

And E-Verify isn’t foolproof. Foreign workers can also easily produce high-quality fake documents.

A police department in Maine recently tangled with the White House over the hiring of an officer who was cleared to work by the federal E-Verify system but who was later found to be in the country illegally.

In response to that case, Assistant Secretary of Homeland Security Tricia McLaughlin said in a statement that while the E-Verify system is an important tool, using it “does not absolve them of their failure to conduct basic background checks to verify legal status.”

Big-name firms don’t often face major consequences

The laws are on the books to prosecute or penalize employers who hire undocumented workers, but federal prosecutors have rarely gone after big-name firms, Owsley said.

In April, the Trump administration fined two Denver-based cleaning companies $6.2 million and $1 million, respectively, for hiring dozens of unauthorized workers. That same month, prosecutors ordered the multimillion-dollar seizure of 14 properties, seven bank accounts and 15 vehicles from a Chinese staffing company they accuse of laundering money and supplying foreign workers to an Ohio factory.

They were large busts, but not of companies that are household names.

“It’s been used against employers with a lowercase ‘e,’” Owsley said of past workplace enforcement. “It’s not the Hyundais of the world, it’s not the Tysons of the world. It’s a lot of times a restaurant that serves some kind of Asian cuisine or some kind of Mexican cuisine. It’s a tool in the federal prosecutors’ arsenal that the federal prosecutors are not using.”

During a news conference Sept. 5, Schrank, the federal agent, said investigators are still trying to figure out who hired the illegal workers at the Georgia construction site. He said the criminal investigation is ongoing.

“As we had determined through our investigation in advance and certainly experienced yesterday, there was a network of subcontractors, and subcontractors for the subcontractors there,” Schrank said. “So, the employees worked for a variety of different companies that were on the site. It was not just the parent company, but also subcontractors. We continue to work on the investigation of who exactly worked for what companies.”