SALT/START treaties limit the nukes we got and can put on warheads officially. Unofficially it isnt that difficult to design a missile to carry 20-40 warheads if we truly wanted to. As far as a mobile launcher goes, politics will kill any ground based version right now.

Why should we cut back our nuclear force while China is beefing up theirs?

Becasue China is about forty years behind us? We have such massive overmatch against any opponent except, perhaps, Russia (assuming their weapons still work, which seems to be in doubt), I don't know that this is the place we need to be spending our limited resources right now.

a few years back one of the PLA generals threated us to nuke L.A if we interfere their "liberation" against Taiwan. As a San Diego resident I felt threatend by his words, I say we take'em out before they do anything stupid to us.

Um...like I said politics. Officially we got 2500 or "active" nukes on missiles ready to launch. Unofficially the numbers closer to about 22,000 warheads that are still in storage and ready to be put back onto missiles. Its one the things the russians still hate about the way we do it, we dont destroy the warheads, just the nose cap on the missile (even though all you have to do is switch out new nose caps). Basically what it means is that in a bad going into worse case scenarios is that theres more than enough nukes still in our arsenal to nuke every city on the globe and then nuke the rubble.....twice.