The United States Air Force (USAF) is the aerial warfare branch of the United States Armed Forces and one of the seven uniformed services. Previously part of the United States Army, the USAF was formed as a separate branch of the military on September 18, 1947.

The USAF is the largest and most technologically advanced air force in the world, with about 6013 manned aircraft in service (4,282 USAF; 1,321 Air National Guard; and 410 Air Force Reserve); approximately 160 Unmanned Combat Air Vehicles, 2161 Air-Launched Cruise Missiles, and 500 Intercontinental Ballistic Missiles; and as of September 30, 2006, had 334,200 personnel on active duty, 120,369 in the Selected and Individual Ready Reserves, and 107,000 in the Air National Guard. An additional 10,675 personnel were in the Standby Reserve and the Air Force employed 168,558 civilian personnel.