The Cold War held a shaky peace through the use of a strategy known as Mutual Assured Destruction (MAD). As a result of the nuclear arms race of the 1950’s and 1960’s, both the United States and the Soviet Union possessed enough thermonuclear weapons and ballistic missiles to instantly theoretically destroy all human life on earth several times over. Moreover, both sides developed early warning satellite and radar systems, along with hardened silos and mobile platforms (such as bombers, submarines, and wheeled launchers). This allowed either side to detect and survive a first strike for long enough to launch a full-scale retaliation against the attacker. Therefore, a first strike would be suicidal and kept both the U.S. and the USSR from attacking. The payoff matrix for a MAD strategy would be:

The ‘-9′ payoff assumes that the first strike manages to slightly cripple the full retaliatory capabilities of the victim (this assumption does not change the outcome). The Nash equilibrium is clearly “Not First Strike/Not First Strike”, which also happens to be Pareto optimal. This equilibrium prevented the Cold War from erupting into full-scale nuclear war.

With the Cold War over, the United States and Russia have taken radically different approaches to the maintenance and upgrade of their nuclear stockpiles. “The Rise of U.S. Nuclear Primacy”, an article by the Foreign Affairs newsletter, describes how the U.S. has become the sole dominant member in this nuclear club. While the U.S. keeps putting money into nuclear research & development and keeps its first-strike submarines on patrol, the Russians have let their mobile platforms deteriorate and their early-warning systems develop dangerous holes. As a result, a first strike by the U.S. has a high chance of eliminating most of Russia’s retaliatory capabilities. A first strike by Russia would also pack less of a punch. The payoff matrix has thus evolved to:

Although the Nash equilibrium is still the Pareto-optimal “Not First Strike/Not First Strike”, the U.S.’s “Not First Strike” strategy is no longer as dominant as it was before, since the “First Strike” U.S. payoff has increased dramatically. If the Russian retaliatory capability is entirely eliminated, MAD ceases to be an applicable strategy. At that point, there will no longer be a distinct Nash equilibrium. However, we can hope that the U.S. will not launch the first strike because doing so is not Pareto optimal (i.e. does not maximize social welfare for both the U.S. and Russia). As the game theory computer realizes in the 1983 film WarGames, “The only winning move is not to play.”