Proxy war
EXCERPTs:
Cold War
1) Proxy wars were common in the Cold War, because the two nuclear-armed superpowers (the Soviet Union and the United States) did not wish to fight each other directly, since that would have run the risk of escalation to a nuclear war (see mutual assured destruction). Proxies were used in conflicts in Afghanistan, Angola, Korea, Vietnam, the Middle East, and Latin America.


2) In the Korean War, the Soviet Union and the People's Republic of China aided the Communists in North Korea against the US-led United Nations forces. The Soviet Union did not enter the war directly, though it was alleged that the Soviets had sent pilots to fly MiG 15s for the Communists. China, however, did enter the war directly and sent thousands of 'volunteers' in 1950 preventing the U.N. coalition from defeating the Communist government of the north.

Mutual assured destruction
EXCERPT:
Mutual assured destruction (M.A.D.) is a doctrine of military strategy and national security policy in which a full-scale use of nuclear weapons by two opposing sides would effectively result in the destruction of both the attacker and the defender.[1] It is based on the theory of deterrence according to which the deployment of strong weapons is essential to threaten the enemy in order to prevent the use of the very same weapons. The strategy is effectively a form of Nash equilibrium, in which both sides are attempting to avoid their worst possible outcome, in this case, nuclear annihilation.