F-4 Phantom II non-U.S. operators are the non-U.S. nations with air forces that operate or used to operate the McDonnell Douglas F-4 Phantom II. The Phantom II entered service with the U.S. military in 1960 and served until 1996. During this time it was the primary interceptor, air superiority fighter and fighter bomber with the U.S. Navy, Marines and Air Force. The Phantom II was exported to 11 other nations, and continues to serve in a military role in some parts of the world. Australia In March 1963, McDonnell Douglas offered to provide the RAAF with a modified version of the F-4C, the model 98DX, fitted with SNECMA Atar 9 engines. This engine was already used in the RAAF's Mirage IIIOs, but the French turbojet was inferior to the General Electric J79, and the RAAF chose instead to order the F-111C Aardvark which had a greater range. Since the development of the F-111 was plagued with many setbacks, it was expected that the order for the RAAF would not be ready before 1974, leaving the Australian air force short of a suitable aircraft. The need to replace their Canberra B.20s was frustrated by the delay in the development of the F-111. The solution was to loan F-4Es to the RAAF, under the Peace Reef program. On 22 June 1970, the contract was signed, and the first of 24 new F-4Es arrived the following September. They served with Nos. 1 and 6 Squadrons, both based at RAAF Base Amberley. The Australian aircrews praised the choice and the F-4Es were so well received that their popularity threatened the F-111C order at one point. The first six aircraft were returned in October 1972, with another five returned in November 1972. The first six F-111Cs were delivered in June 1973, and the rest of the F-4Es were returned to the United States Air Force. In 1972 the United States offered to sell the leased aircraft to Australia. Earlier, the Americans had offered to sell 48 aircraft, including RF-4Es if the RAAF had cancelled the F-111C. On balance, the F-4 would need to be supported by eight Boeing KC-135 Stratotankers to achieve the endurance required in Australian service with in-flight refueling, making the whole package uneconomical compared to the F-111C with its greater range. Also, acquisition of the Phantom would have required disbanding at least one Mirage squadron in order to provide the necessary aircrew