That effort compromised the encrypted radio systems used by the FBI’s mobile surveillance teams, which track the movements of Russian spies on American soil, according to more than half a dozen former senior intelligence and national security officials. Around the same time, Russian spies also compromised the FBI teams’ backup communications systems — cellphones outfitted with “push-to-talk” walkie-talkie capabilities. “This was something we took extremely seriously,” said a former senior counterintelligence official.
Exclusive: Russia carried out a 'stunning' breach of FBI communications system, escalating the spy game on U.S. soil
Russian compounds and diplomats in the U.S. played key roles in a counterintelligence operation that stretched from the Bay Area to the nation’s capital, according to former U.S. officials.