The 4520th Combat Crew Training Wing was designated from the 4520th CCTG on 1 May 1961, and the Combat Crew training squadrons were renumbered. The 4537th Fighter Weapons Squadron had been assigned F-105D Thunderchiefs in March 1961, and the wing taught veteran pilots in all phases of fighter weapon employment: air-to-air gunnery, rocketry, conventional and nuclear bombing, aerial refueling, and combat navigation. The F-4 Phantom II Instructor Course began in mid-1965 and during the Vietnam War, experienced combat pilots were used as Fighter Weapons instructors at Nellis. On 1 January 1966 the USAF Fighter Weapons School was activated at Nellis with F-100, F-4, and F-105 divisions and on 1 September 1966, Fighter Weapons School elements and the 4520th CCTW merged to activate the 4525th Fighter Weapons Wing.