Why do ballistic/ICBM missiles have such a long time before they can be fired?

Question

e.g. was just reading about some cold war era missiles that from launch command needed 30 minutes to be able to be launched.

In: 3

Answer 1

yeah as other have said it’s so they can be fuelled as they had liquid propellant which could not be left in the missile for extended periods. If you watched the recent Space X Starship launch, you could see them fuelling that right before they launched. A lot of modern missiles are solid fuel so can be fired much faster as the fuel is already in place.