Why the Suddenly Aggressive Behavior by China?

In the Los Angeles Times, AHS speaker Gary Schmitt discusses why Beijing is shedding its low profile — and causing regional waves:

"Perceived U.S. weakness cannot be the whole story, even if it's an important part. What are also at play are Chinese ambitions. China's leaders want their nation to be a great power; they want China, as in its imperial past, to have a predominant say in the region."