The US Department of Justice (DOJ) announced Thursday that it had seized millions of dollars’ worth of cryptocurrency from terrorist organizations al-Qassam Brigades, al Qaeda and the Islamic State of Iraq and the Levant (ISIS).

The details of this operation, dubbed by the DOJ as the government’s “largest ever seizure of terrorist organizations’ cryptocurrency accounts,” were revealed in three forfeiture complaints and a criminal complaint unsealed in Washington, DC, on Thursday. The US seized “millions of dollars, over 300 cryptocurrency accounts, four websites, and four Facebook pages” as part of the operation.

In the first unsealed complaint, the DOJ alleged that al-Qassam Brigades asked for bitcoin donations on social media and then on its websites in 2019. The donations were not anonymous, so Internal Revenue Service (IRS), Homeland Security Investigations (HSI) and FBI agents tracked and seized all 150 cryptocurrency accounts that transferred money to and from the accounts. The US also issued criminal search warrants for all US-based subjects who donated to the campaign.

In the second complaint, the government claimed that al Qaeda and affiliated terrorist groups also used social media to launder bitcoin money. At times, the groups allegedly acted as charities while “openly and explicitly soliciting funds for violent terrorist attacks.” The third complaint alleged that Murat Cakar, an ISIS facilitator, operated a website that claimed to sell FDA-approved N95 respirator masks. The website, FaceMaskCenter.com, actually sold fake personal protective equipment.

On the operation, Secretary of the Treasury Steven Mnuchin said:

Terrorist networks have adapted to technology, conducting complex financial transactions in the digital world, including through cryptocurrencies. IRS-CI special agents in the DC cybercrimes unit work diligently to unravel these financial networks. Today’s actions demonstrate our ongoing commitment to holding malign actors accountable for their crimes.