China in a land war, IMO could only operate for a relatively short period of time outside of its own country. Beyond their borders their aren't many highways or nice terrain to ease of transport of logistical support. China has enough trouble as it is in its own country(which they are fixing). But the farther they get away from their borders, the harder logistical support that will have and the size of their military will make things ALOT worse. A big military is very nice, but supporting it is a pain in the ass. And as Is a war over an ocean is logistically impossible for them.