Perhaps they don't want collapse of the U.S.; perhaps they would prefer to supplant the U.S.
To accomplish that, they could simply quit extending credit to us, and maybe sell some of the debt on the open market. This would tend to drive the dollar down and interest rates up - it would, therefore, damage the U.S. economy.
We've given them a variety of weapons. They can choose the time and method most advantageous to them. Maybe that will be during a face-off over Taiwan.
"To accomplish that, they could simply quit extending credit to us, and maybe sell some of the debt on the open market. This would tend to drive the dollar down and interest rates up - it would, therefore, damage the U.S. economy."
??? so they sell the debt on the open market - dosen't that presume that they would find a willing buyer ?
... and the dollar going down hurts their own, as it it tied to the dollar - If they cut loose from the dollar and it sinks, their products become more expensive for us. Their VCR factories become idle, and no more green pieces of paper for them - unless they come back here and buy something we produce, they simply have green pieces of paper.