 If the Soviets were building missiles in the numbers being predicted by the CIA and others within the defense establishment, by as early as 1961 they would have enough to attack all SAC and ICBM bases in the US in a single first strike.It was later demonstrated that this "missile gap" was just as fictional as the "bomber gap" of a few years earlier, but through the late 1950s, it was a serious concern.The Air Force responded by beginning research into survivable strategic missiles, starting the WS-199 program.