Doesn't that depend on how they're set up? I'd imagine in the 50+ years since they've been invented they would have designed it so it could, specifically because modern anti missile defenses exist.
I mean, I know world governments can be dumb, but I would imagine they're not that dumb as to bother maintaining a key super weapon just to not upgrade it / design it so that it won't work if used.
But any knowledge on how modern triggering works on them I'd imagine would be kept a state secret wouldn't it? I don't think it's something you'd want others to know.
Someone has to know because scientists and engineers are educated in universities and not in military boot camps. Universities are the origin of all scientific expertise in a nation, including the nation's military.