Stu-6, first two examples coming to mind:
A Chinese general threatened to use nuclear weapons.
The official line is that they will use force in case Taiwan declares independance, the direct implication of which is use of force against the US (because of alliance).

Also of consequence is how the Chinese dictatorship would handle themselves in a strong international position (assertiveness, need to unite people, etc). I remember reading that asian societies tend to want a hierarchy rather than a multipolar system.

I think the Chinese would gain more from draining the US of information by sending their people to the universities and spies in the industries rather than conquering it. If you'd have a threat from the Chinese in that case, it would be more of isolation and affecting opinion and policy in the US.

Just IMHO...

Martin