noun. The branch of an intelligence service charged with keeping sensitive information from an enemy, deceiving that enemy, preventing subversion and sabotage, and collecting political and military information.

noun. counterespionage

noun. intelligence activities concerned with identifying and counteracting the threat to security posed by hostile intelligence organizations or by individuals engaged in espionage or sabotage or subversion or terrorism

"He claimed that he himself was a member of the CIA (a charge he later recanted) and said he had been recruited “between 1970 and 1971” and trained in counterintelligence in Panama and Venezuela."

intelligence  intelligence activity  intelligence operation  

censoring  censorship  counter-sabotage  counter-subversion  counterespionage  

antitrust  backstabbing  counterdrug  counterespionage  counterterrorism  

bugging  cloak-and-dagger work  counterespionage  electronic surveillance  espial