I'm certainly not an expert on nuclear brinkmanship:). I only know that orbital nuclear bombardment capabilities is something that nuclear states desire but are

I'm certainly not an expert on nuclear brinkmanship:). I only know that orbital nuclear bombardment capabilities is something that nuclear states desire but are MAD-destablizing enough to have been ruled out via treaties. I assume the problem with subs is prompt communication. Also they are more of a retaliatory strike weapon thank first strike capability.