The corner-stone of American Foreign Policy during the Cold War, & today still. What it really comes down to is a balance, "....and the balance is the understanding that if either side initiates the use of nuclear weapons, the other side will respond with sufficient power to inflict unacceptable damage. Mutual Assured Destruction. So Mutual Assured Destruction is the foundation of stable deterrence in a nuclear world. It's not mad, it's logical." - Robert McNamara, Secretary of Defense during the Kennedy and Johnson administrations, & the man regarded as the Father of the doctrine of Mutually Assured Destruction. A doctrine so simple, but one that works so well.