In many respects the most successful, versatile and widely-used combat aircraft of the post-war era the F-4 Phantom II was quickly adopted by the USAF after its spectacular US Navy introduction. It was so much better than any other USAF fighter at the time that Air Force generals were happy to comply with the US government's 'commonality' policy and purchase a naval aircraft. As an interceptor it was superior to the existing F-106A Delta Dart and it combined outstanding fighter characteristics with the ability to carry more ordnance than many WW II bombers and offered the possibility of a sophisticated reconnaissance variant. McDonnell had provided the USAF with both fighter-bomber and reconnaissance versions of its successful F-101 Voodoo and the Phantom offered the same twin-engined reliability, sturdy engineering and reliability but with the clear advantage of multiple missile armament and long-range radar.
Its introduction to USAF squadrons happened just in time for the Vietnam conflict where USAF F-4Cs took over MiG-fighting duties from the F-100 Super Sabre, freeing it and the F-105 Thunderchief to fly attack sorties instead. Although the F-4 was never intended as a dog-fighter to tangle with light, nimble, gun-armed MiGs it was responsible for destroying 109 MiGs in aerial combat. More often, Phantoms deterred MiGs from attacking US bombers, or delivered ordnance themselves. Reconnaissance RF-4Cs replaced RF-101C Voodoos, offering far more advanced data-gathering devices.
Elsewhere, F-4C and F-4D Phantoms re-equipped Tactical Air Command squadrons in Europe, Japan and the USA and they were joined by later models. In Vietnam numerous MiGs had also been destroyed by gun-armed F-105 and F-8 fighters and even by Phantoms with 'strap-on' gun-pods, lending weight to the argument that the Phantom should also have an internal gun. In its original naval interceptor role this had been considered unnecessary but the USAF sponsored development of the F-4E with the same built-in gun as the F-105 in addition to its existing missiles and other ordnance. In the early 1970s further funding added wing slats to improve the F-4E's manoeuvrability, an updated cockpit and a television-based, long-range visual sighting system to identify possible enemy aircraft. USAF Phantoms also took over the nuclear alert role combining this with air defence or conventional ordnance delivery as required.
For a very different scenario some F-4Es were modified as replacements for the F-105G Wild Weasel. With sophisticated radar detection equipment and anti-radiation missiles these F-4Gs were still in service in 1991 and they provided invaluable service during Operation Desert Storm, as did the remaining RF-4C reconnaissance Phantoms. At the end of their careers many of the survivors from the 3,380 'land-based' Phantoms were converted into target drones for training purposes. Others were passed on to Air National Guard or Reserve units before becoming drones or joining five air forces in other countries. New aircraft were also built for West Germany, Iran and Israel while 140 F-4EJs were assembled or entirely built under licence in Japan. With the Israeli Air Force F-4s achieved notable success in combat.
The USAF's experience with the Phantom showed clearly that the air-to-air fighter was still a necessity and its decision to fund its successor, the McDonnell-Douglas F-15 Eagle (as well as the F-16 Fighting Falcon and F-22A Raptor) was heavily influenced by the lessons of US and other Phantom pilots in combat.