We would fuck china right up the ass, no lube.
It would be like this:
Seriously. There are so many levels on which the US military is superior. Plus, we can use the technology and tactics for modern wars, and our soldiers are experienced. China's army is prepared well for a zerg rush, and that's not how it goes down in the 21st century.
China's troops are unprepared for a modern war, all they've been doing for the past half-century is slaughtering their own people while us dicking around in the middle east will pay off big.