Following the Falklands War in 1982, Prime Minister Margaret Thatcher's government decided to station RAF Phantoms there in defense of the islands. However, the RAF's Phantoms were fully tasked in support of NATO and couldn't be spared, and so in 1983 Britain ordered 15 ex-US Navy F-4J Phantoms to augment RAF stocks, allowing a Phantom squadron to be sent to the Falklands. The "new" aircraft received the designation "F-4J(UK)". They were originally provided essentially "as-was", but they were gradually refitted with more and more British kit, including some gear scavenged from surplus Phantom FG.1s.

At first, RAF pilots regarded the isolated Falklands as a hardship duty post, but they were provided with a "coastel", a floating hotel, with comfortable accommodations, and also found that the isolation meant that they could fly with very few restrictions in largely empty airspace. The stories of British pilots flying back, forth, and then over flocks of penguins to make them fall over backwards appear to be a tall tale, however.

Beginning in 1978 248 F-4Js were brought up to "F-4S" standards, with structural strengthening; leading-edge slats; a substantially updated AN/AWG-10A radar set and other new avionics; and uprated J79-GE-10B engines, which also featured improvements to eliminate the tendency of the J79 to leave behind a trail of dirty smoke, a liability in combat. Fit of the leading-edge slats required removal of the BLC system.

The F-4C was followed in USAF service by the "F-4D", which performed its first flight on 9 December 1965, leading to initial service deliveries in 1966. The F-4D would be the USAF's workhorse over Southeast Asia. 825 were built into 1968.

The F-4D airframe was basically the same as that of the F-4C; the primary enhancements were in avionics, particularly AN/APQ-109 radar. The AN/APQ-109 was an improved, more reliable "hybrid" version of the AN/APQ-100 with solid-state components in the low-voltage sections. The F-4D also featured new attack and navigation systems, and uprated 30-kilowatt electric power generators.

Since combat experience over southeast Asia had shown the need for a gun, a 20-millimeter cannon pod designated the "SUU-16/A" was hastily introduced, to be eventually replaced by the similar but improved "SUU-23/A". The F-4D was wired for carriage of the cannon pod, and had an ASG-22 lead-computing gunsight fitted for aiming it. Apparently some F-4Cs were also retrofitted to carry cannon pods.

The AN/AAA-4 IRST was deleted in most F-4D production, since it had proven useless in practice. Confusingly, late production F-4Ds were fitted with the fairing used for the AN/AAA-4, but it contained elements of an AN/APR-25/26 radar warning receiver (RWR), not an infrared sensor.