Nuclear weapons are useful, but nuclear war is not. This is the fundamental contradiction from which the nuclear impasse springs. Weapons of unprecedented destructiveness, with the potential under the wrong conditions to destroy civilization, are thereby extremely useful in preventing war. Nor is the preventive role imaginary. Europe now knows an extended period of peace, or at least absence of armed conflict, which must be laid at the door of the nuclear arsenals available to the superpowers, among others. He who would change the balance of power in Europe must first find a way around the balance of terror. Worse for the person who would change the status quo, the balance of terror is basically dyadic. A multipolar system would at least have the virtue of flexibility; a bipolar system does not. Although the U.S. and Soviet relationships with their respective allies are now more sensitive to national differences than in the past, the superpower sovereignty in the capability for nuclear first strike and retaliation is still unique.
This condition of superpower nuclear sovereignty shared across a divided East-West political glacis creates ironical outcomes below the nuclear threshold. The impetus for improvement in capabilities to wage conventional war was increased. These improved capabilities for conventional war fighting would be useful if the war could be contained below the nuclear threshold. To that extent they would contribute deterrence by denial. However, the nuclear components of a future battlefield in Europe could not be isolated completely from the conventional. Even if not used, nuclear weapons would hang over the battlefield like unwelcome evil spirits. The issue whether either the North Atlantic Treaty Organization (NATO) or the Warsaw Pact could