Assuming Perimeter worked as intended, it would finish the job automatically eliminating the fear that no one would be alive to fire a retaliatory strike. Moscow would not longer have to fire their nuclear weapons in a panic.
During the Cold War, MAD implied you had to be suicidal to launch a nuclear strike against another nuclear-armed adversary—the adversary fires everything in retaliation and kills you. So the mission in a first-strike shifted to taking out the adversary's leadership preventing them from launching a retaliatory strike. This created a situation where the US and the Soviets were incentivized to fire at the slightest provocation: if Moscow thinks Washington launched a nuclear strike, Moscow better fire before American nukes come down.
With the Dead Hand, Moscow could activate Perimeter which would listen for certain indications of nuclear strikes and if it was determined that a nuclear strike occurred, automatically launch Soviet nuclear weapons in retaliation.
> Assuming Perimeter worked as intended, it would finish the job automatically eliminating the fear that no one would be alive to fire a retaliatory strike. Moscow would not longer have to fire their nuclear weapons in a panic.
> ...This created a situation where the US and the Soviets were incentivized to fire at the slightest provocation: if Moscow thinks Washington launched a nuclear strike, Moscow better fire before American nukes come down.
> With the Dead Hand, Moscow could activate Perimeter which would listen for certain indications of nuclear strikes and if it was determined that a nuclear strike occurred, automatically launch Soviet nuclear weapons in retaliation.
If the Russians developed Perimeter to address these concerns, what did the US do? I'd assume it built more resilient command and control infrastructure with more delegation, because Russia seems less comfortable with decentralization than the US, but I don't really know.
During the Cold War, MAD implied you had to be suicidal to launch a nuclear strike against another nuclear-armed adversary—the adversary fires everything in retaliation and kills you. So the mission in a first-strike shifted to taking out the adversary's leadership preventing them from launching a retaliatory strike. This created a situation where the US and the Soviets were incentivized to fire at the slightest provocation: if Moscow thinks Washington launched a nuclear strike, Moscow better fire before American nukes come down.
With the Dead Hand, Moscow could activate Perimeter which would listen for certain indications of nuclear strikes and if it was determined that a nuclear strike occurred, automatically launch Soviet nuclear weapons in retaliation.