North Korea has built a secret workforce inside American companies. Using stolen identities, AI tools and U.S. accomplices, its operatives have cheated their way into remote jobs in an effort to earn money for Kim Jong Un's regime. The FBI says there are thousands of them applying for jobs across America.

The Wall Street Journal's documentary, "Infiltrated: North Korea's Secret U.S. Workforce," follows a single cell of these operatives. Drawn from a trove of leaked data -- browser history, emails, calendars and screen recordings pulled from the team's own computers -- our yearlong investigation offers a rare look at how North Korea's undercover workers get hired.

Here's what we learned:

AI gets them hired

The cell we tracked applied for jobs at more than 1,000 companies in just over three months, using AI at nearly every step. We can see them using AI to write convincing cover letters and résumés. Screen recordings showed them reading directly from ChatGPT in response to interview questions. And, as hiring managers have gotten better at catching them, the workers have even begun using AI face-swapping tools to make themselves harder to spot.

They rely on help from Americans

A company laptop mailed to Pyongyang would be a nonstarter, so North Korean IT workers pay American facilitators to run their devices in the U.S. while the workers patch in remotely. Facilitators -- some witting, some not -- also open bank accounts, cash checks and sit for some interviews. One Ohio man told us he even attends company meetings while the North Koreans do the actual labor. On a $75,000-a-year job, he said they split the salary 50/50.

They are stealing identities and upending lives

North Korea's IT workers use stolen American identities to pass hiring screenings. The workers often juggle multiple aliases simultaneously, and can hold down several jobs under each stolen name. The consequences can be devastating for those caught up in the scheme. We spoke to a Georgia man whose identity was posted for sale online and used by North Koreans to work at jobs around the country. He says he is now unable to open a bank account, qualify for loans or rent a home.

Their salaries fund North Korea's military

Some of the North Korean IT workers earn as much as $300,000 a year, and the Treasury Department has found up to 90% of their salaries flow back to the regime -- with the operation earning as much as $800 million annually by recent estimates. Our investigation followed the money through a network of North Korean IT workers and cybercriminals, eventually reaching a company sanctioned in the U.S. in connection to Pyongyang's weapons program.

Watch here: