 In any conceivable scenario where both sides had similar numbers of ICBMs, the US forces would survive a sneak attack in sufficient numbers to ensure the destruction of all major Soviet cities in return.The Soviets would not risk an attack under these conditions.Considering this "countervalue" attack concept, strategic planners calculated that an attack of "400 equivalent megatons" aimed at the largest Soviet cities would promptly kill 30% of their population and destroy 50% of their industry.