Hawker Siddeley Harrier AV-8As to the AV-8C configuration—the work focused mainly on extending useful service lives and improving VTOL performance. The AV-8C and the remaining AV-8A Harriers were retired by 1987. These were replaced by the Harrier II, designated as the AV-8B, which was introduced into service in 1985. The performance of the Harrier in USMC service led to calls for the United States Air Force to procure Harrier IIs in addition to the USMC's own plans, but these never resulted in Air Force orders. Since the late 1990s, the AV-8B has been slated to be replaced by the F-35B variant of the
Hawker Siddeley Harrier overcome efforts to obstruct its procurement. The AV-8A entered service with the Marine Corps in 1971, replacing other aircraft in the Marines' attack squadrons. The service became interested in performing ship-borne operations with the Harrier. Admiral Elmo Zumwalt promoted the concept of a Sea Control Ship, a 15,000-ton light carrier equipped with Harriers and helicopters, to supplement the larger aircraft carriers of the US Navy. An amphibious assault ship, , was converted into the "Interim Sea Control Ship" and operated as such between 1971 and 1973 with the purpose of studying the limits and possible obstacles for operating such a