 However, due to delays in the F-35 program, all USAF F-16s will receive service life extension upgrades.The F-16's first air-to-air combat success was achieved by the Israeli Air Force (IAF) over the Bekaa Valley on 28 April 1981, against a Syrian Mi-8 helicopter, which was downed with cannon fire.On 7 June 1981, eight Israeli F-16s, escorted by six F-15s, executed Operation Opera, their first employment in a significant air-to-ground operation.