to lobbying by Sir Frederick Handley Page, a desire to retain jobs in the aviation industry, and because the government wanted the Rolls-Royce Conway engine produced for the Vickers VC10 airliner. Nuclear mission The British government was well aware of the devastation that a nuclear war would bring. A 1953 report estimated that an attack on the UK with 132 fission weapons would generate 2 million casualties. A follow-on study, which considered the possible effect of hydrogen bombs, estimated that as few as ten could reduce the entire UK to a radioactive ruin. Given that defence was impractical, the UK turned to a policy of deterrence, by targeting the population and administrative centres of the Soviet Union. In 1957, the Air Ministry drew up a list of 131 Soviet cities with populations of 100,000 or more. Of these, 98 were within of the UK. Of these, 44 were selected. It was estimated that their destruction would kill about thirty percent of the urban population of the Soviet Union, about 38 million people. It was almost inconceivable that a war with the Soviet Union would not involve the United States, and as early as 1946, American defence planning envisaged using the UK as a base for nuclear strikes on the Soviet Union, as the United States Air Force (USAF) had not yet developed long-range bombers that could attack key targets in the Soviet Union from bases in the United States. But the United States strategy was that attacks on population centres would have little value once a war had actually begun, and prioritised military targets, particularly those from which nuclear weapons could be launched or deployed. Coordination of war plans between RAF Bomber Command and the USAF Strategic Air Command (SAC) was clearly desirable, and a joint war plan was negotiated between 1954 and 1958. The RAF's nuclear force was capable of destroying key targets before bomber aircraft from the United States had entered Soviet airspace, "taking into account Bomber Command’s ability to be on target in the first wave several hours in advance of the main SAC force operating from bases in the United States." Based on the assumption that RAF Bomber Command would have about 100 V bombers in operations by 1959, the SAC/RAF agreement assigned 106 targets to the UK: 69 cities, 17 long-range aviation bases, and 20 air-defence sites. Attacks on the air-defence installations would clear the