This from that link:

"Relations between China and Japan deteriorated to the lowest point in five years during the 17-day detention of a Chinese fishing boat captain before Japanese authorities last week decided to release him. China opposed U.S.-South Korea military exercises aimed at deterring North Korea, and dismissed regional efforts to mediate maritime territorial claims." (emphasis added / kw)

This is just the latest iteration in the NE Asia who's in charge game, it all -- say again, all -- has been going on cyclically for over 50 years, the fact that you are now paying attention to it doesn't move any of it to major crisis status...

The fact that China now has enough money to be more assertive is obvious and well known. Noting their capability -- accurately -- is wise. 'Predicting' what they will do is less so. Over 12 years in Asia and the ME taught me that attempts to predict intentions in those areas is borderline futile, the thing I did learn was to be alert. We're doing that and that's adequate.