China stopped buying US debt a long time ago. Not only that, but they sold off much if not all of the US debt they owned
First sentence you had is correct. Second is incorrect. Chins still owns 1.2T in ust
China still holds $1.2 trillion of US debt and is the largest foreign debt-holder.
https://www.thebalance.com/who-owns-the-u-s-national-debt-3306124
It is very difficult for China to off-load their US debt if they continue as a major trading partner with the US.
It is the modern version of Mutual Assured Destruction. :-)
Not according to the U.S. Treasury.