U.S. officials say that hackers supported by the North Korean government stole more than $400 million in cryptocurrency using fake video calls and impersonation.

According to the FBI, the U.S. federal police, more than 900 people have been targeted by this form of fraud in the past 18 months, which the agency calls “face-stealing” (sarin-meaning: face stealer).

“North Korea’s government relies on revenue from large-scale cryptocurrency thefts to finance its illegal weapons program and has stolen billions of dollars in recent years,” said Brett LeDerman, an executive in the FBI’s cybercrime division.

The news is published one week after Binance, the world’s largest cryptocurrency exchange, announced that hackers stole more than $6.3 billion worth of cryptocurrency from the company using fake job interviews.

Law enforcement agencies in the United States have attributed the cyberattack on Binance, which they consider the largest crypto theft in history, to actors linked to North Korea. Pyongyang has denied the claim.