MAD, for example. It was used in strategic thinking to refer to the possibility of mutual annihilation in the nuclear era; because attacking an enemy with nuclear capability could lead to your own elimination, then mutual deterrence restrained the two superpowers of the Cold War. MAD means Mutual Assured Destruction.
I´ll give you a second one: "Domino theory." It was a foreign policy notion risen in the 1950s in the USA. President Eisenhower said that if French Indochina fell into communist hands, then other countries of Asia would follow , one after another as in the domino game.
