The Soviet Perimeter, also known by the West as the “Dead Hand,” was a Cold War automatic nuclear control system that could unleash all nuclear weapons at once without any human command if the Soviet/ Russian state is threatened.

Developed during the early 1980s, the Perimeter was meant for a first strike on the United States if the Soviet Union detected a nuclear attack, and all its communications were severed or its Armed Forces in disarray. This control system is tied to all nuclear weapons of the Soviet arsenal, 1600 tactical nukes, 2400 strategic nukes, and intercontinental ballistic missiles capable of delivering a combined destructive warhead that could wipe a country off the map in 30 minutes without a counter-retaliation. This was part of a broader Cold War doctrine of mutually assured destruction, where one side that initiated the first strike would also be destroyed.

To activate these nuclear weapons, the system would measure the communication, radiation levels, heat, air pressure, and short-seismic disturbances. After taking these factors into consideration and confirming it’s a hostile nuclear attack, the perimeter would launch a command rocket with a radio warhead that would transmit orders to all nuclear silos without the issue of being radio jammed. Thus causing all warheads to be launched.

The Perimeter became part of Soviet contingency plans as nuclear tensions rise between East and West.

https://www.military.com/history/russias-dead-hand-soviet-built-nuclear-doomsday-device.html

https://www.britannica.com/technology/doomsday-machine#ref1195943

https://en.wikipedia.org/wiki/Dead_Hand

https://www.defencexp.com/what-is-russias-dead-hand-system/