Washington and London are jointly accusing Russia's government of targeting global internet equipment for political and economic espionage.
The two governments said the operations, which allegedly involve planting malware on internet routers and other equipment, could also lay the foundation for future offensive cyberattacks.
A joint statement Monday by the U.S. Department of Homeland Security, the FBI and the UK's National Cyber Security Centre says the targets include public and private internet equipment, but provides no details.
A companion technical alert says both nations have "high confidence" in the finding. It adds that state-sponsored Russian cyber-meddling has been reported by multiple sources since 2015. The alert urges affected companies and public sector organizations to take action to harden poorly-secured devices, but cites just one specific product.