The Tornado F3 was selected for development from the original Tornado GR1 attack aircraft in the late 1970s as the RAF's dedicated fighter following an MoD review of other NATO candidate aircraft. A total of 170 were ordered. The main visible difference from the GR1 or GR4 attack aircraft is the longer fuselage, which permits greater internal fuel stowage. It entered service at an interim F2 standard with the RAF in 1985. A year later, initial deliveries of the definitive Tornado F3 were made. Fitted with the long range Foxhunter radar and more powerful engines, the aircraft successively replaced Lightning and Phantom fighter squadrons in the air defence role. Seven squadrons were formed, two of which were subsequently disbanded in view of the reduced threat of air attack to the UK. The variant is also in service with the Royal Saudi Air Force and until the end of 2004 the Italian Air Force leased Tornado F3 aircraft from the RAF. The pilot in the front seat flies and fights the aircraft, while the rear seat weapons systems officer controls the radar and defensive countermeasures systems. An important feature of the F3 is its ability to patrol at long distance from its base, supported by air-to-air refuelling. The aircraft is capable of operation in all weathers and at night, using night-vision goggles. In its usual air defence role, the F3 can receive real-time information on approaching targets through a datalink from patrolling Airborne Early Warning Sentry aircraft and attack nominated targets using AMRAAM missiles. In the anti-radar role, F3s can pass information on the location of an opponent's radar site back to the Sentry or ground-stations for onward relay to other aircraft or ground forces. Under the AMRAAM Optimisation Programme, these aircraft are being modified to engage several targets simultaneously with greater accuracy and a higher probability of success.