The Treasury Department’s Financial Crimes Enforcement Network (FinCEN) designated Bitzlato, a Hong Kong-registered cryptocurrency exchange, as a “primary money laundering concern” in the first use of a law that targets entities that facilitate illicit Russian financial transactions.

FinCEN announced Wednesday that Bitzlato “plays a critical role in laundering convertible virtual currency (CVC) by facilitating illicit transactions for ransomware actors operating in Russia, including Conti, a ransomware-as-a-service group that has links to the government of Russia.” A multinational law enforcement effort shut down Bitzlato and seized its assets, officials said.

FinCEN and the Department of Justice (DOJ) said Bitzlato became a haven for laundering the proceeds of criminal activity, and its administrators knew the platform was “rife with illicit activities.” Many of its users were criminals who could access the platform without providing their identities or were conducting their activities under others’ identities, the DOJ said.