China has been spoiling for a fight (with anyone) for quite some time ever since it began to think itself a Great Power (with scores to settle).
Has any one else been paying attention to the latest sword rattling by China over some tiny islands that Japan claims and have lots of oil close by?
A lot of big wars get started over small territories.
The first act of this war may be a rare thing -- economic war to start. And attempt to undermine the Japanese economy by selling off the bonds China owns.
It's also a test to see how staunch an ally the US will be when push comes to shove.
China, like Russia's Putin, knows that Obama is a weakling who wants a weak America. This is the time to push, to prick and prod and see how the sleeping giant reacts.
The thing about China (and Russia) is that they don't play. They are always seeking an advantage, an empire, a hegemony. Realpolitik is what they are and do. They know nothing else and care for nothing else. It's their DNA whereas Great Britain felt that way for awhile, especially when the money was good, but they lost heart since they were in it for the money (and some poetic glory) alone. Once the money quit rolling in and started costing them, they gave it up.
Like us. All we ever wanted to do once some colonizing aspirations died in the early 20th century, is sell people cokes and hamburgers. We just want to make some money and if being the signal Super Power helps, then by all means. For us, it's all about the do re mi.
But for Russians, Chinese, and (probably) Germans, its all about the power and the wonderful feeling it gives them. Money is not the main object.
Let's see how far China wants to push this. Japan has no nukes or much of a self-defense force. Are we really going to be their umbrella? Are our skirts that wide still?