The United States Armed Forces are the military forces of the United States. United States federal law establishes six armed forces: the Army, Marine Corps, Navy, Air Force, Space Force, and Coast Guard, each assigned specific roles and operational domains. With the exception of the Coast Guard, which operates under the Department of Homeland Security (DHS) in peacetime, the services are organized under the Department of Defense (DoD).
Established during the American Revolutionary War, the Army and the Navy, and later the other services, have played a decisive role in the country's history. They contributed to early national consolidation through conflicts such as the Barbary Wars and the War of 1812, shaped the country's territorial evolution, and were involved in global conflicts including World War I, World War II, the Cold War, and the war on terror. The National Security Act of 1947 reorganized the military establishment by creating the DoD, the Air Force, and the National Security Council; in 1949, an amendment to the act merged the cabinet-level departments of the Army, Navy, and Air Force into the DoD. formalizing a unified defense structure under civilian control. The Space Force was established in 2019 as the newest branch.
