Safety Through Certain Loss
Mutually assured destruction is a doctrine of military strategy, and its logic is uncomfortable. It holds that if one nuclear armed country attacks another, and the defender can still strike back, both are wiped out. Nobody wins, so nobody starts.
It rests on rational deterrence: the belief that the threat of a weapon stops an enemy from using the same weapon. Strategists describe the situation as a form of Nash equilibrium, where once both sides are armed, neither has any reason to attack and neither has any reason to disarm.
The doctrine makes a strange demand. Neither side may build shelters on a large scale, and neither may build effective missile defences. Protection sounds like the obvious thing to want, but under this logic it is destabilising: a country that has less to fear from a counter attack becomes more willing to attack first.
Supporters call the outcome a nuclear peace. Critics answer that spreading these weapons raises the odds of one being used by accident or by someone outside any government.
The Acronym Was the Argument
The phrase was coined in 1962 by Donald Brennan, a strategist at the Hudson Institute. He was not endorsing it. Brennan built the acronym deliberately so that it spelled the English word mad, his way of arguing that holding weapons capable of destroying a whole society was irrational.
The underlying idea was almost a century old by then. Writing during the Franco-Prussian War in 1870, the English author Wilkie Collins hoped for the discovery of an agent so terrible that war would mean annihilation and fear would force people to keep the peace. Jules Verne described something similar in 1863 in a novel that went unpublished until 1994.
Weapons inventors said it too. Richard Gatling patented his gun in 1862 partly to show the futility of war, and after inventing dynamite in 1867 Alfred Nobel hoped that once two armies could destroy each other in a second, nations would recoil from war entirely. History did not oblige.
Standing on Three Legs
The United States became the first nuclear power in August 1945. The Soviet Union tested its own device on 29 August 1949. At first neither could reach the other effectively, but long range bombers changed that, and American policy became what the Secretary of State called instant retaliation.
The doctrine needed something more reliable: a guaranteed second strike, meaning the ability to hit back after absorbing a surprise first strike. The United States first tried to get it by keeping bombers permanently in the air near Soviet borders, which was expensive and fragile.
Submarines solved it. Starting with the George Washington class in 1959, ballistic missile submarines could hide at sea, and an enemy could not realistically find and destroy all of them at once. By the Cuban Missile Crisis of 1962, submarine launched missiles completed the third leg of the nuclear triad, alongside land based missiles and bombers. Robert McNamara set the doctrine out formally in the early 1960s. The same arrangement runs today, and submarines are the United Kingdom's only nuclear deterrent.
Every Assumption Can Fail
The doctrine only works if several things are always true, and each one has been tested.
It assumes perfect detection, with no false alarms in the systems that report an incoming attack. During the Cold War there were several false positives, the best known involving the Soviet officer Stanislav Petrov. It assumes perfect attribution too, though a launch from a submarine or from a shared border can be genuinely hard to trace.
It assumes perfect rationality, including that no individual commander can force the decision. That nearly failed during the Cuban Missile Crisis, when an argument broke out aboard a Soviet submarine cut off from radio contact and the second in command, Vasili Arkhipov, refused to agree to a launch.
American war games called Proud Prophet tested whether a limited nuclear strike was possible. Every attempt escalated into a full exchange. After that, American plans shifted their emphasis back toward conventional forces.
