Mutually Assured Destruction (MAD)

Mutual assured destruction (MAD) is a doctrine of military strategy in which a full-scale use of nuclear weapons by one of two opposing sides would effectively result in the destruction of both the attacker and the defender. 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 — nuclear annihilation.

Source: http://en.wikipedia.org/wiki/Mutual_assured_destruction

A very simple theory but powerful only because it holds true; I sure hope so because trouble is brewing in the Middle East with Washington threatening Iran.