The Justice Department’s seizure of $6.1m in funds tied to alleged ransom payments, announced alongside fresh sanctions against a cryptocurrency exchange and arrests of alleged hackers, marked an escalation in Washington’s attempt to weaken hacking groups that have disrupted US businesses.

The retrieval of funds shows how victim companies’ cooperation with law enforcement can sometimes pay off, US officials said on 8 November, while sanctions will create additional questions for US businesses faced with hackers’ ransom demands.