The inability to protect your population is a crucial element of the fragile stability of mutually assured destruction (MAD). Taking steps to protect your population appears to the Soviet Union as an attempt to gain a major advantage and perhaps even a first-strike capability. The Soviet Union responds with nuclear strikes before your can fully protect your population and potentially seize a victory. Strategic stability in a nuclear standoff is extremely fragile. Even a seemingly harmless move such as this can plunge the world into nuclear war. Your attempts to protect your populace will likely destroy human society as we know it.