In the United States, the JCS comprises senior uniformed leaders of the United States Department of Defence. They act in an advisory capacity on military issues to the President of the United States, the Secretary of defence, the Homeland Security Council and the National Security Council. The JCS headquarters is located in the Pentagon.
The JCS has a legal definition by statute and consists of the Chairman of the Joint chiefs of staff (CJCS), Vice Chairman of the Joint Chiefs of Staff (VCJCS), chiefs of staff of the military branches (Army, Marine Corps, Navy, Air Force, Space Force), and the chief of the National Guard Bureau.
Each military chief of staff, outside of their duties in the JCS, report and work directly for the Secretary of their military department.
The origins of the JCS in the United States date back to the Joint Board system which was established in 1919 to coordinate between the army and the navy.