Nuclear deterrence is a military strategy that relies on the threat of nuclear retaliation to prevent adversaries from initiating conflict. The concept is rooted in the doctrine of mutually assured destruction (MAD), where the use of nuclear weapons by one nation would result in the complete annihilation of both the attacker and defender. During the Cold War, this principle kept the U.S. and Soviet Union from engaging in direct military conflict, as both possessed enough nuclear weapons to destroy each other many times over. Deterrence assumes that rational actors will avoid war if the consequences are catastrophic enough, leading to strategic stability despite underlying tensions.