The United States Air Force is one of the seven American uniformed services and acts as the aerial warfare branch of the United States Armed Forces. The core functions of the U.S. Air Force include nuclear deterrence operations, command and control, personnel recovery, global precision attack and agile combat support.
The U.S. Air Force traces its roots back to 1907, when the U.S. Army Signal Corps formed an Aeronautical Division. From there, it progressively became known as the Aviation Section of the Signal Corps, the Division of Military Aeronautics, the U.S. Army Air Service, the U.S. Army Air Corps and the U.S. Army Air Forces. The U.S. Air Force was then officially established on September 18, 1947.
The U.S. Air Force operates more than 5,638 military aircraft, 450 intercontinental ballistic missiles and 63 military satellites, as of 2012. The Air Force has 309,339 active-duty personnel, 185,522 civilian personnel, 71,400 Air Force Reserve personnel and 106,700 Air National Guard personnel. It maintains a $140 billion budget, as of 2015, making it one of the largest and most well-funded Air Forces in the world. The Chief of Staff of the Air Force represents the Air Force on the Joint Chiefs of Staff.