 FAIR: ! Col. Mustard said that he stole essential Air Force parts  during World War 2. However, the Air Force became a separate branch  of the military after World War 2. During World War 2, what became  the Air Force was the Army Air Corps.  * Adding further information  Col. Mustard said that he stole essential Air Force parts during  World War 2. The Air Force became a separate branch of the military  after World War 2. During World War 2, what became the Air Force was  the Army Air Corps. However, some returning airmen may have already  been calling themselves Air Force officers 