There are two bits of context you need to understand this.
First: Early nuclear missiles weren't very accurate - you don't have to be very accurate when your target is the size of Moscow. A missile silo is a much smaller target!
So AIUI missile silos were hardened to survive a nuclear bomb landing 500m away - but they wouldn't survive a direct hit.
Second: There was a theory, at one point in the cold war, that one side could launch a surprise attack that struck and disabled the other side's nuclear weapons. Or at least, disabled a large enough fraction that the counterattack was survivable.
This was seen as winning. Or as close to winning as you can get, in a nuclear war. And it was seen as relatively more ethical than targeting cities.
The jargon for this is "counterforce" or "disarming" strike [1] and it was part of the rationale for having a ridiculous number of bombs - if you have enough bombs to destroy the world 10 times over, you can destroy the world even if 90% of your bombs have been destroyed in a surprise attack.
Later in the cold war other technologies were developed - high precision guidance, submarine launched missiles, and missiles with multiple warheads. Between them they made a disarming strike seem unlikely to work. But on the other hand there are still an awful lot of missiles around and they gotta be targeted somewhere. If you'd already sent a dozen at the pentagon and a dozen at the white house, why not send some of the remainder at a few nuclear silos?
Of course, you might well say this all seems pretty unlikely. A nuclear war? In this day and age? But people who think that probably aren't in the market for a disused nuclear bunker, except as a historical curiosity.
First: Early nuclear missiles weren't very accurate - you don't have to be very accurate when your target is the size of Moscow. A missile silo is a much smaller target!
So AIUI missile silos were hardened to survive a nuclear bomb landing 500m away - but they wouldn't survive a direct hit.
Second: There was a theory, at one point in the cold war, that one side could launch a surprise attack that struck and disabled the other side's nuclear weapons. Or at least, disabled a large enough fraction that the counterattack was survivable.
This was seen as winning. Or as close to winning as you can get, in a nuclear war. And it was seen as relatively more ethical than targeting cities.
The jargon for this is "counterforce" or "disarming" strike [1] and it was part of the rationale for having a ridiculous number of bombs - if you have enough bombs to destroy the world 10 times over, you can destroy the world even if 90% of your bombs have been destroyed in a surprise attack.
Later in the cold war other technologies were developed - high precision guidance, submarine launched missiles, and missiles with multiple warheads. Between them they made a disarming strike seem unlikely to work. But on the other hand there are still an awful lot of missiles around and they gotta be targeted somewhere. If you'd already sent a dozen at the pentagon and a dozen at the white house, why not send some of the remainder at a few nuclear silos?
Of course, you might well say this all seems pretty unlikely. A nuclear war? In this day and age? But people who think that probably aren't in the market for a disused nuclear bunker, except as a historical curiosity.
[1] https://en.wikipedia.org/wiki/Counterforce