Thirteen agencies make up the U.S. intelligence community, an umbrella organization led by the CIA director. It's advised by inside and outside experts who constitute the National Intelligence Council. The National Security Agency is largest of the 13. The others:
Central Intelligence Agency: Foreign intelligence and counterintelligence. Its employment Web site is the only one offering jobs in "clandestine service."
Defense Intelligence Agency: Assesses targets and battle damage in wartime, monitors weapons proliferation and crises in peacetime. Sometimes supports U.N. operations and U.S. allies. Air Force, Army, Marine Corps and Navy each have intelligence corps.
National Reconnaissance Office: Operates intelligence satellites. Existence of the 40-year-old space-intelligence office became widely known only in the 1990s.
National Imagery and Mapping Agency: Maps and topographical photography for civil and military uses.
Federal Bureau of Investigation. Principal enforcer of federal law is also involved in protecting the United States from foreign espionage and terror. Runs background checks on nominees to sensitive government positions.
State Department: Its intelligence arm provides analysis of foreign affairs.
Energy Department: Intelligence arm monitors foreign energy activity and is charged with protecting U.S. energy secrets.
Treasury Department: Provides liaison between the intelligence community and Treasury's law enforcement arms, and helps prepare intelligence budget proposals.