The Joint Chiefs of Staff (JCS) is the body of the most senior uniformed leaders within the United States Department of Defense, which advises the president of the United States, the secretary of defense, the Homeland Security Council and the National Security Council on military matters. The composition of the Joint Chiefs of Staff is defined by statute and consists of a chairman (CJCS), a vice chairman (VJCS), the chiefs of the Army, Marine Corps, Navy, Air Force, Space Force, and the chief of the National Guard Bureau. Each of the individual service chiefs, outside their JCS obligations, works directly under the secretaries of their respective military departments, e.g. the secretary of the Army, the secretary of the Navy, and the secretary of the Air Force.

Following the Goldwater–Nichols Act in 1986, the Joint Chiefs of Staff do not have operational command authority, either individually or collectively, as the chain of command goes from the president to the secretary of defense, and from the secretary to the regional combatant commanders. Goldwater–Nichols also created the office of vice chairman, and the chairman is now designated as the principal military adviser to the secretary of defense, the Homeland Security Council, the National Security Council and the president.

The Joint Staff (JS) is a headquarters staff in the Pentagon, composed of personnel from each of the six service branches, that assists the chairman and the vice chairman in discharging their responsibilities and is managed by the director of the Joint Staff (DJS).