COVID-19 USA Daily Numbers, page-112

Too busy fighting among themselves. 'China' as we know it, is a western construct. It's made up of many regions and they have fought viciously among themselves. It's the reason for the Great Wall. But more importantly, China's been focussed internally because poverty has been the driver for political instability.
Therefore the main focus has been on raising living standards. That's been the trade-off for keeping the CCP regime in charge.
Right now the entire system is under strain from Xi's confrontational approach to other nations. To the extent that it adversely affects trade, and ripples into reversing the economic gains to hundreds of millions, it will affect Xi's leadership.
China is profoundly aggressive but it's passive-aggressive.
Further, past performance is not necessarily indicative of future performance.
Xi has moved from passive-aggressive to open aggression, but it's also possible that they will bend if international pressure is brought to bear.
It's early days yet for an expansionist China but they've been busily laying the foundations.
IMO