In the early years of the Cold War, the majority of the bomber force of the US Strategic Air Command (SAC) was made of Boeing B-29 Superfortress bombers, and later its successors, the Boeing B-50 Superfortress and the Boeing B-47 Stratojet, all of which lacked the necessary range to reach targets in the Soviet Union from bases in the continental United States. Even small number of Convair B-36 Peacemaker bombers could not make it there and back. Overseas bases were therefore required, and the need for bases in the UK was a feature of American war planning for over a decade.