Golly:  quite a few posters point out that China is in fact the largest holder of US debt, for example in bonds. Apparently China could dump those bonds and call those debts. Quite a threat.

Since bond holders or lenders are in the business of getting repaid, in this case dumping bonds or calling debts would be like allowing a mortgagee  to burn their mortgage AND keep the house. Unless of course you have the muscle to repossess that house and toss out the inhabitants, and  I see that as a rather  unlikely development in this case.

As the old, but updated, saying goes: "if you owe the bank a thousand dollars, you have a problem. If you owe the bank a trillion dollars, the bank has a problem.."

Who has the worst problem in this situation?