The largest national debt ever-what will happen when it's called in?

Question

The Chinese hold most of our National Debt. The US wants to alter trade agreements.
What happens when we can't make the interest payments & they start forcloseing on the debt ?

Answer 1

We would declare a trade embargo on Chinese goods, and their economy would tank. They would never "call in" the USA debt they own. It would be suicide for them.

Answer 2

Just pay Russia with Alaska and Mexico with New Mexico and Japan with Hawaii.