A major government contractor kept American workers in “slave-like conditions,” confiscated their passports, and forced them to work around toxic chemicals with no protection, according to a previously unreported lawsuit.

The lawsuit alleges that the outsourcing firm ManTech defrauded the federal government while violating a landmark anti-slavery law. If the lawsuit is successful, it will deal a body blow to one of the Pentagon’s biggest contractors. A spokesperson for ManTech said the company does not comment on ongoing litigation. Earlier this month, the company filed a motion to dismiss the suit saying the lawsuit was based on “undeveloped legal theories and scattershot allegations.”

The lawsuit says ManTech “relied upon forced labor to illegally sacrifice its employees’ health and safety in pursuit of a higher profit margin.”

The allegations detailed involve a contract worth more than $2 billion for mechanic work on Mine-Resistant Ambush-Protected vehicles, or MRAPs. The massive vehicles have V-shaped hulls designed to deflect IEDs—a life-saving technological innovation for soldiers in Iraq and Afghanistan. Because troops ride in these vehicles in dangerous conflict zones, they get hit—and need repairs.

That kind of work often takes place on the sprawling American military installations in tiny Kuwait. Such accusations are not rare in the oil-rich countries that flank the Persian Gulf. Saudi Arabia, Qatar, and the United Arab Emirates have all drawn sustained criticism for their treatment of migrant workers. Workers from Pakistan, Nepal, Bangladesh, India, and the Philippines have flocked to the region to find themselves in abusive work environments with limited options for leaving. Qatar’s alleged abuse of migrant laborers in the lead-up to the 2022 World Cup has drawn widespread condemnation.

“It’s very common in the Gulf region, for migrant workers, particularly low wage migrant workers to have their passports confiscated upon arrival,” said David Segall, a research scholar at New York University who has studied migrant labor abuse in the Gulf.

“ ManTech supervisors allegedly ordered their employees to misreport how much time they worked servicing the vehicles. The plaintiffs say this was so the Pentagon wouldn’t realize that the company was using unqualified mechanics to do the work. ”

What is unusual is the fact that American citizens are making them. Segall said he hadn’t been aware of anything like it before. “I’ve not heard of this particular phenomenon for Western migrant workers or expatriates. Passport confiscation is fairly more common for low wage migrant workers who either don’t have the education to fight back or don’t have a secure place to store the passport or don’t have the leverage to say anything,” he added.

Enter ManTech. On May 31, 2012, the company signed a contract with the Pentagon to service MRAPs. The contract ended up being worth $2.85 billion—real money, even in the military’s bloated budget. In the months after getting the contract, ManTech hired a number of Americans to go to Kuwait and service the vehicles. According to the lawsuit, they recruited far and wide—including fast food workers, participants in a program for high school dropouts, and people with little to no experience as mechanics.

The lawsuit, filed in Washington, D.C., federal district court, has six plaintiffs. According to the suit, all six men took jobs with ManTech for this contract. ManTech promised to get them the requisite work papers. They signed contracts promising to pay the company thousands of dollars if they quit before working for two years. And they flew to Kuwait.

When they arrived in country, something strange happened, according to the suit: ManTech employees confiscated their passports, and didn’t give them work visas. Instead, the men got tourist visas—and then were put to work. Since they didn’t have their passports, they couldn’t leave or apply for legal authorization. And since they’d signed a contract promising to pay ManTech significant sums of money if they quit, the plaintiffs felt they had no choice.

When they started working, things got worse. MRAPs are coated with chemical agent resistant coating (CARC) paint that’s highly toxic when pulverized. According to a handbook from the Army’s Combined Arms Center in Fort Leavenworth (PDF), surfaces covered with this material should never be welded or cut, and people working around it should wear “high-efficiency air purifying respirators, protective goggles, gloves, and other protective clothing.”

The plaintiffs say they were kept in an unventilated space, and much of their work involved welding and cutting MRAP surfaces coated with this paint—and that they didn’t get any safety equipment.

“The air was polluted with the smoke of burning CARC paint caused by the arc-welding of MRAP vehicles, the grinding of CARC paint and metal by sanders, fossil fuels released through engine exhaust, fumes from petroleum products, and other toxin released by employees’ abrasive work on MRAP vehicles,” the lawsuit reads.

ManTech didn’t run fans to ventilate the area, according to the suit, and didn’t test the air quality.

ManTech supervisors also ordered their employees to misreport how much time they worked servicing the vehicles into the military’s labor-tracking system, under threat of firing, according to the suit. The plaintiffs say this was so the Pentagon wouldn’t realize that the company was using unqualified mechanics to service the vehicles.

“ The plaintiffs say they were kept in an unventilated space, and much of their work involved welding and cutting MRAP surfaces coated with this toxic paint—and that they didn’t get any safety equipment. ”

None of the plaintiffs ever got visas, the suit alleges. Instead, when their tourist visas neared expiration, ManTech supervisors took them to the airport, gave them their passports, and put them on flights to Bahrain. As soon as they landed in Bahrain, they turned around and flew back to Kuwait, where their tourist visas were renewed. One ManTech supervisor called the process “turn and burn,” according to the suit.

The lawsuit also claims that the plaintiffs were unfairly fired for pushing back against ManTech’s allegedly unlawful activity.

The plaintiffs describe behavior that breaks all sorts of federal laws, including laws that require government contractors to abide by host countries’ labor laws, laws barring contractors from lying to the federal government about the work they do, and a law against human trafficking.

Their litigation is under the False Claims Act, landmark and complex legislation designed to let whistleblowers sue their current or former employers for defrauding the government. ManTech’s motion to dismiss the lawsuit argues that the plaintiffs do not give enough detail to support their allegations that the company defrauded the government.

“The Government contracted for the repair and maintenance of MRAP vehicles, and relators do not allege that the Government did not get what it paid for,” the motion to dismiss reads.

The motion also says that since some of the men were fired, they couldn’t have been forced to work. ManTech’s attorney calls this an “inconsistency” which makes the plaintiffs’ claims “implausible on their face.” And it says ManTech did not actively coerce the men into working for the company, and did not explicitly threaten them with deportation or imprisonment—punishment for breaking Kuwaiti labor laws—if they quit.

The plaintiffs’ attorney will have to respond to ManTech’s motion to dismiss within the next few weeks.

The company could soar even if it loses in court. ManTech appears to be poised to benefit from the conflict in Syria; Zacks, an investment research firm, listed it as the number one stock to buy in response to the chemical weapons attack on the rebel-held city of Douma, Syria. The site noted that ManTech’s stock has made significant gains in the last six months. ManTech announced earlier this month that it has inked two deals—worth $104 million total—to service vehicles for the Marine Corps.

And the company is well-respected within the Beltway; just last month, the company’s CEO, Kevin Phillips, testified before the Senate intelligence committee on security clearance reform. In that testimony, Phillips highlighted the importance of his company’s work and workforce.

“The slow pace of the security clearance process prevents us from recruiting and hiring the talented individuals critical to national security,” he said.

—with additional reporting by Adam Rawnsley