The United States Air Force (USAF) is the aerial and space warfare service branch of the United States Armed Forces and one of the seven American uniformed services. Initially part of the United States Army, the USAF was formed as a separate branch of the U.S. Armed Forces on 18 September 1947 under the National Security Act of 1947. It is the most recent branch of the U.S. Armed Forces to be formed. The USAF is the largest and one of the most technologically advanced air forces in the world. The service articulates its core functions as Nuclear Deterrence Operations, Air Superiority, Space Superiority, Cyberspace Superiority, Command and Control, Global Integrated ISR, Global Precision Attack, Special Operations, Rapid Global Mobility, Personnel Recovery, Agile Combat Support, and Building Partnerships.
The U.S. Air Force is a military service organized within the Department of the Air Force, one of the three military departments of the Department of Defense. The Air Force is headed by the civilian Secretary of the Air Force, who reports to the Secretary of Defense, and is appointed by the President with Senate confirmation. The highest-ranking military officer in the Department of the Air Force is the Chief of Staff of the Air Force, who exercises supervision over Air Force units, and serves as a member of the Joint Chiefs of Staff. Air Force combat and mobility forces are assigned, as directed by the Secretary of Defense, to the Combatant Commanders, and neither the Secretary of the Air Force nor the Chief of Staff have operational command authority over them.