Less important than SAC or MAC, but increasingly significant in a changing world, was the Air Force's Tactical Air Command (TAC). By 1965, TAC was providing the aircraft and hardware for the major build-up of US air power in Vietnam and at bases in Thailand. F-100 Super Sabres and F-105 Thunderchiefs were still populous in TAC but the 'century series' of supersonic fighters was beginning to give way to the bent-wing, twin-engined McDonnell F-4C Phantom. The Air Force had lowered itself, in manner of speaking, in acquiring the F-4C Phantom (soon to be joined by F-4D and F-4E models) from an aircraft designed for, and pioneered by, its arch adversary, the US Navy.

TAC was always a 'holding' command and had never been given a combat mission. When its aircraft deployed, they came under USAFE (US Air Forces in Europe) or PACAF (Pacific Air Forces) control. F-4C Phantoms deployed to Asia initially on temporary duty (TDY) before being transfered on a more lasting basis. The Republic F-105 Thunderchief became the workhorse of the 1965-68 Rolling Thunder campaign against North Vietnam, but only after aircraft and pilots were readied for the fighting by TAC's hard-working combat crew training units at stateside bases. General William W. Momyer, TAC chief from 1965 to 1968, was an architect of doctrine and tactics for the new war now unfolding, and was one of the fighter pilots who, as a result of the Vietnam War, were to wrest control of the Air Force from the 'bomber generals.'

By late 1965, the need for replacement air crews in South East Asia was critical. To meet this need, TAC dropped virtually all other operations to train aircrews. By mid-1966, Twelfth Air Force units in particular were busily engaged in training combat crews. To support this mission, Replacement Training Units were activated at TAC bases and provided a steady stream of aircrews to the combat area.

TAC people at their stateside bases worked mightily to learn lessons from the faraway conflict and to put improvements into effect. The 1965 decision to apply camouflage to tactical aircraft ended an era of colorful markings and reduced the vulnerability of these warplanes to both the naked eye of the enemy and his infra-red acquisition gear. 'Lessons learned' included a very qualified approval of the air-to-air missile which had become the standard weapon for a fighter. The AIM-4 Falcon and AIM-7 Sparrow semi-active radar homing missiles performed well much of the time but required major fixes. The AIM-9 Sidewinder infra-red missile, a 'heater' in pilot jargon, was more reliable but only at closer distances. The conclusion was inescapable that it had been a mistake to delete the gun from the fighter aircraft. Although F-4 Phantoms of the 1960s were not armed with a cannon until the F-4E model became operational in 1968, every American fighter developed thereafter was armed with a cannon.

Beyond all else, however, the 1960s taught TAC and the Air Force the importance of dissimilar air combat manoeuvre (ACM) training and led to the 'aggressor' squadrons of the following decade.