Which agency monitors counterintelligence activities in the United States?

The FBI Counterintelligence Division plays a crucial role in monitoring and managing counterintelligence activities within the United States. This division is specifically tasked with protecting the country from espionage and other intelligence threats posed by foreign intelligence services and individuals. It conducts investigations, gathers intelligence, and implements countermeasures to thwart any adversarial actions that may harm national security.

The FBI's focus on counterintelligence is essential because it encompasses a wide range of activities, including the detection and prevention of spying, the collection of sensitive information, and the protection of government and private sector assets. The agency operates under a law enforcement model, allowing it to investigate these issues and collaborate with other intelligence community members and federal agencies to ensure that the nation's security interests are defended.

In contrast, while the other agencies listed may have intelligence and security roles, they do not primarily focus on domestic counterintelligence activities in the same comprehensive way as the FBI. The NSA, for instance, is more centered on signals intelligence and foreign communications, the CIA primarily deals with foreign intelligence operations, and the Department of Defense oversees military matters and national security policy rather than being directly involved in internal counterintelligence oversight.