A U.S. court has charged three Russian nationals for allegedly operating sanctioned cryptocurrency mixing services that North Korean cybercriminals have used to launder stolen virtual funds, continuing recent efforts to crack down on illicit cyber activities funding Pyongyang’s nuclear ambitions.

A federal grand jury in the Northern District of Georgia indicted Roman Vitalyevich Ostapenko, Alexander Evgenievich Oleynik and Anton Vyachlavovich Tarasov for their alleged roles in running the cryptocurrency mixing services Blender.io and Sinbad.io, the Department of Justice announced in a press release on Friday.

Ostapenko, 55, faces one count of conspiracy to commit money laundering and two counts of