I don't want to see it, but I am curious how a massive global war with China as a primary military power would go.

I have a feeling that they'd get rocked early on by more battle-hardened nations, like the US and Russia, especially the former who has a military who has been in a constant state of conflict for about 20 years now.

I also don't think they'd be invadable (at least without power armor, 'natch), but they'd likely also have a hell of a time projecting any power out to their immediate neighbors without swift retaliation.

The US is even still the dominant naval power within their own oceanic reach, so there's no way they'd own the sea lanes either.

Like you said, their power lies more in subversion and spycraft than direct conflict.