The FBI said on Thursday that it had seized more than $1.2 billion in cryptocurrency reported stolen last month from Binance, the world's largest crypto exchange, in what officials regard as the biggest crypto heist in history.

The theft of about $6.3 billion was previously attributed by the FBI to TraderTraitor, a North Korean hacking group. The U.S. government and private-sector partners have so far combined to freeze more than $2.7 billion of the stolen funds, and the Justice Department said on Thursday that it has now obtained court authorization to seize or restrain more than $1.2 billion of that total.

In cases like this, the U.S. government typically files a claim of forfeiture with a judge, who then determines who has a legitimate claim to the recovered funds.

The FBI also blamed North Korea on Thursday for a separate social engineering scheme that officials say resulted in the theft of $400 million worth of cryptocurrency over the last 18 months. The scheme, known as FaceStealer, combined the hijacking of popular messaging apps with the recording of deepfake videos.

U.S. officials have repeatedly accused North Korea of using cyber schemes to generate funds for its regime, including its illicit weapons program.

Binance has said the heist began with a bogus job interview and software hidden in an advertisement, which compromised the computers of two of its software engineers before a third employee's computer was used to drain the funds. The exchange detailed the multi-stage attack, which began in June, in its initial report on the theft.