The AV-8B was developed as a second-generation Harrier, primarily for the US Marine Corps. The Harrier II entered USMC service in 1984 and participated extensively in the 1991 Gulf War; it is routinely deployed onboard amphibious assault ships.
The Harrier II fleet, which equips seven operational squadrons, has gone through two avionics upgrades to the baseline version, and through a re-manufacturing programme. A night-attack sensor upgrade equips four squadrons. The Harrier II+, which incorporates the night-attack upgrades and the APG-65 multi-mode radar, equips two squadrons. A re-manufacture programme was intended for 72 aircraft and involved replacement of the Pegasus F402-RR-406 engine with the increased-thrust -408A version.
The upgrade also included APG-65 radar, a navigation infra-red set, night vision goggles-compatible cockpit, exterior lighting, and a moving-map display. AV-8Bs are also going through an avionics upgrade with fitment of a GPS, the common missile approach warning system, frequency-agile digital radios, and the digital Advanced Target Hand-off System, and all are gaining the ability to deploy JDAMs. The US is trying to fund an advanced targeting infra-red set for the Harrier. The two-seat TAV-8B, used by the Harrier training squadron, was also upgraded with the F402-RR-408A engine.
The first foreign operator was the Spanish navy which received 12 EAV-8Bs, eight AV-8B Plus and a single EV-8B trainer for operation from the carrier Principe de Asturias. The Flotilla de Aeronaves is having its nine surviving EAV-8Bs converted to the Plus standard. Italy's Marina Militare bought 18 AV-8B Harrier II Plus, including two two-seaters, for operation from the carrier Giuseppe Garibaldi. The Harriers of both navies are primarily tasked with fleet defense of their respective carriers, and have recently gained AIM-120B AMRAAM missile armament.