China has been flexing it's muscles. It is expanding it's borders rather aggressively. It is not showing up at WTO complaints because the other party was the Philippines and China can out wrangle them.
China is a sincere threat.
It is changing it's stance.
The phone call with Taiwan put the frosting on the cake.
China is moving aggressively because it can.
China is moving past the 'idea' it is the billionaires happy place with jobs for Chinese citizens. The Chinese government is not invested in it's economy, it's oligarchs are invested in the Chinese economy.
China is a communist country. The Chinese economy that so many American million-billionaires-wanna-be covet is not coveted by the Chinese government. If China loses it's middle class tomorrow and the wealthy oligarchs leave to protect their wealth, the Chinese government could not care less.
If the Chinese government witnesses it's people return to Third World status then that is the way it is and the communists will find a way to insure their existence. The Chinese government wants a better quality of life for it's citizens, but, if the progress made is a threat to it's sovereign status, China will shed it as a deception and start over again.