What is the name of the doomsday device in Dr. Strangelove?

The name of the doomsday device in Dr. Strangelove is the Doomsday Machine.

In the film, the Soviet Union secretly builds it as a nuclear deterrent. The device consists of buried cobalt bombs programmed to detonate automatically if the country suffers a nuclear attack. Because it cannot be switched off once triggered, the resulting radioactive fallout would make Earth's surface uninhabitable for decades.

The machine is revealed in the Pentagon War Room by Soviet Ambassador Alexei de Sadeski, just as the United States is trying to recall General Ripper's rogue B-52 bombers. Dr. Strangelove points out the machine's major strategic flaw: deterrence works only if the enemy knows the weapon exists. The Soviet leadership planned to announce it publicly the following week, but the timing is disastrously late.

A common mix-up is calling it the “Doomsday Device,” a phrase often used generically for weapons of planetary destruction. In the film, “Doomsday Machine” is the canonical name. The concept also draws on Cold War ideas about cobalt-salted bombs and automatic retaliation.