McDonnell Douglas F-4C Phantom II, USAF Users, part two

On 10th July 1965, some F-4C from the 45th Tactical Fighter Squadron, of the 15 Tactical Fighter Wing, operating from Ubon, in Thailand, scored USAF's first aerial victory against a North Vietnamese MiG-17 with an AIM-9 Sidewinder air-to-air missile.
Later, on 26th April 1966, a MiG-21 was shot down by an F-4C of the 480th Tactical Fighter Squadron and, a little bit earlier, on 24th July 1965 another F-4C from the 45th Tactical Fighter Squadron became the first American aircraft to be shot down by an enemy surface-to-air-missile (SAM). On 5th October 1966 another F-4C became the first American aircraft to be shot down by an air-to-air missile shot from a North Vietnamese MiG-21.
The earliest versions suffered from leaks in wing fuel tanks that had to be re-sealed after each flight and at least 85 of them were found to have crack in outer wing ribs and stringers. Problems were also found in aileron control cylinders, electrical connectors, and engine compartment fires.

Sources:
1. https://en.wikipedia.org/wiki/McDonnell_Douglas_F-4_Phantom_II#United_States_Air_Force
2. Salamander Books - The Complete Book of Fighters