My pet theory is that this was said specifically to destabilize the US. As others have said, this is not new. China has been saying this for a long time. But 100% the GOP is going to call Biden weak for not shutting Xi down and instead saying the US supports a "One China Policy " without any critical thought as to what the dynamics are.
This is to fire up the right wing base.
No, most of the debt is owned domestically by the people