I think China had no choice in 2015. The collapse of the stock market, spurring the capital outflow (currently, 3 Trillion of 6 Trillion of China's wealth is overseas) and induced by the 'corruption crackdown' by Xi Jing Ping, exposed the fragile economic condition in China (350% debt/gdp). China realized it was playing a severely weak hand, and it had to act belligerent in its own self interest. So it

- threatened several of its neighbors with occupying and later arming the islands in SCS

- threatened to invade Taiwan

- ramped up hacking efforts to steal IP around the world

- told its citizens to stop buying from Korea after the missile crisis

- told its citizens to stop buying from Japan after the island issue

- propping up dictatorships around the world

this is all in an effort to redirect the world to look away from its demographics decline, growth flatlining, reshoring and factories moving out of China, etc