Modern American intelligence was born in World War II with the Office of Strategic Services and reorganized by the National Security Act of 1947, which created the CIA. During the Cold War the community grew to include signals intelligence, satellite reconnaissance, and military intelligence agencies. After the September 11 attacks, investigators concluded that agencies had failed to share information, and Congress created the Director of National Intelligence to coordinate them.
This guide maps the 18 members of the community, explains what each does, and describes the oversight system meant to keep secret agencies accountable.
Intelligence work depends on classification, the system that marks information as confidential, secret, or top secret, and on security clearances held by millions of government and contractor employees. Supporters of robust intelligence powers say they are essential against terrorism, espionage, and cyberattacks. Critics across the political spectrum warn of surveillance of citizens, politicization of analysis, and overclassification, concerns raised by leaks such as those of 2013 and by debates over whether agencies act independently of elected leaders.
Eight members of the community sit in the Defense Department. The National Security Agency collects signals intelligence and protects government communications. The National Reconnaissance Office designs and operates spy satellites, and the National Geospatial-Intelligence Agency analyzes imagery and maps. The Defense Intelligence Agency provides military intelligence to commanders and policymakers, and the Army, Navy, Air Force, Marine Corps, and Space Force each have their own intelligence elements.
The Central Intelligence Agency, created in 1947, is the only intelligence agency that stands alone outside a Cabinet department. It collects human intelligence through officers and agents abroad, produces all-source analysis, and is the lead agency for covert action, secret operations that require a written presidential finding and notice to the intelligence committees. The CIA has no law enforcement powers and is barred from internal security functions inside the United States.
The FBI is both a law enforcement agency and an intelligence agency, responsible for counterintelligence and counterterrorism inside the United States, and the Justice Department's National Security Division handles related prosecutions and surveillance applications. The Drug Enforcement Administration has an intelligence office as well. Homeland Security's Office of Intelligence and Analysis shares information with states and localities, and the Coast Guard has its own element. The State Department's Bureau of Intelligence and Research, the Treasury's Office of Intelligence and Analysis, and the Energy Department's intelligence office round out the community.
In 1975 and 1976 the Senate's Church Committee and the House's Pike Committee exposed assassination plots, mail opening, and surveillance of Americans, leading to permanent intelligence committees in the Senate in 1976 and the House in 1977. The Foreign Intelligence Surveillance Act of 1978 created a secret court to approve surveillance of foreign powers and their agents in the United States. Section 702 of the law, which allows collection on foreigners abroad through U.S. companies, has been renewed repeatedly amid debate over how it sweeps in Americans' communications. Inspectors general and a privacy board add further review.
The Intelligence Reform and Terrorism Prevention Act of 2004 created the Director of National Intelligence to head the community, advise the President, and manage the National Intelligence Program budget. The Office of the Director of National Intelligence includes the National Counterterrorism Center and the National Intelligence Council, which produces National Intelligence Estimates. It also oversees the President's Daily Brief, the top-secret summary delivered to the President most days. In 2025 the office announced a major downsizing of its staff and centers.
See how intelligence feeds policy in how foreign policy is made and the National Security Council explained, or compare domestic agencies in federal law enforcement agencies.