What is mutually assured destruction (MAD)?

The logic

MAD rests on one condition: each side must keep enough weapons to strike back after a surprise attack. By the early 1960s, bombers on alert, missiles in hardened silos and missiles hidden in submarines made that possible. If neither side can disarm the other with a first blow, then starting a nuclear war means being destroyed in return. Safety, in this view, comes not from defense but from the certainty of retaliation. Kennedy described the condition in June 1963:

Total war makes no sense in an age when great powers can maintain large and relatively invulnerable nuclear forces and refuse to surrender without resort to those forces.

His televised speech of October 22, 1962, had already turned the logic into policy: any missile fired from Cuba would bring “a full retaliatory response upon the Soviet Union.”

Where the name comes from

The idea is older than the words. In the mid-1960s Robert McNamara, defense secretary under Kennedy and Johnson, made “assured destruction” the yardstick of American nuclear planning: the ability to wreck the Soviet Union as a functioning society even after absorbing a first strike. The acronym is credited to Donald Brennan, a strategist at the Hudson Institute who opposed the doctrine and added “mutual” so the initials would spell a verdict.

What the crisis taught

In October 1962 the logic stopped being theory. Both leaders saw how a war could begin without either of them choosing it: a plane shot down without orders from Moscow, a submarine captain cut off from his superiors, an American spy plane lost over the Soviet Arctic. In Moscow, on the night Kennedy announced the quarantine, Khrushchev told his colleagues, in the notes of that meeting, “We do not want to unleash a war.”

Kennedy put numbers on the danger when he presented the test ban treaty to Americans the following summer:

A full-scale nuclear exchange, lasting less than 60 minutes, with the weapons now in existence, could wipe out more than 300 million Americans, Europeans, and Russians, as well as untold numbers elsewhere.

In the same speech he recalled that Khrushchev himself had warned the Chinese leaders that the survivors of such a war would envy the dead. At American University he had drawn the lesson for both sides: “nuclear powers must avert those confrontations which bring an adversary to a choice of either a humiliating retreat or a nuclear war.”

A wire, a treaty and a clock

The two governments built on that fear in 1963. In August a direct line opened between Washington and Moscow. On August 5, in Moscow, the United States, the Soviet Union and Britain signed the Limited Test Ban Treaty, which banned nuclear tests in the atmosphere, in outer space and under water; the US Senate approved it in September, and it entered into force on October 10, 1963. Tests went on underground. The Bulletin of the Atomic Scientists moved its Doomsday Clock back from seven to twelve minutes to midnight.

MAD did not end the arms race; it shaped it. The ABM Treaty of 1972 strictly limited missile defenses on both sides, on the reasoning that a shield for one would weaken the other’s deterrent. Stanley Kubrick had already turned the doctrine into black comedy. In Dr. Strangelove (1964), the Soviets build a doomsday machine that will destroy the world automatically if they are attacked, then fail to tell anyone it exists, which defeats its only purpose.