[TMSuchman]

You forgot the “Boomer” fleet, the sub launched missiles, & as far as I know they are always up and ready to fly at a moments notice.

[Charles Martel]

The missile boats are more of a second-strike backup to the land-based missiles, and any detected launch at sea (without advance warning to the Russians, Chinese, etc.) would invite disastrous counter-moves, just the same as if we launched from the northern plains.

The smaller tactical nukes, OTOH, can be tough to distinguish from some of the newer conventional bombs - until the radiation sensors start screaming.