Which government agency is know for conducting counterintelligence activities?

The FBI, or Federal Bureau of Investigation, is well-known for conducting counterintelligence activities. It is responsible for protecting the United States from espionage and other threats posed by foreign intelligence services. The FBI identifies and neutralizes threats to national security by investigating cases involving spies and foreign operatives, employing a variety of methods including surveillance, recruitment of assets, and collaboration with other intelligence and law enforcement agencies.

While other agencies, such as the National Security Agency, also engage in activities relevant to national security, the FBI uniquely combines law enforcement capabilities with intelligence functions, making it a key player in the realm of counterintelligence. The Department of State primarily focuses on foreign relations and diplomacy, while the Treasury Department deals with economic and financial matters; neither has the counterintelligence mandate that aligns with the FBI's operational capabilities in this area.