We have some reliable allies in Asia who might make sense to host forward deployments of our nuclear capabilities in the event of a war with China: Taiwan, South Korea, Japan, Australia. If, that is, things got so fraught that they welcomed the deployment. If things got bad enough even India might welcome our topping up their nuclear arsenal with some pointed north instead of at Pakistan.
Though if things got that bad, I don't think Japan would host our nukes. They'd finish assembling their own. (Remember a recent Japanese Defense Minister said, "If Japan decides we need nuclear weapons on Monday, by Friday we will have them." Not an idle boast considering that most of the world's 20 most powerful supercomputer belong to the Japanese atomic energy agency -- you don't need supercomputers to run nuclear power plants; you need them to design nuclear weapons you are sure will work without pre-hostilities testing. Personally I suspect they already have them, and just need to put two halves together, tighten the bolts, and power up the electronics that would trigger the detonation, and they're probably small enough to carry in the weapons bay of a fighter-bomber.)