Countries do not just borrow from other countries, a very large part of the debt is simply created by central banks out of thin air. If the US has enough weapons, and people still need the dollar to buy oil it can do what it wants. China is encircled by US bases. Neoliberalism and globalism have run their course. There was never any real sound economics behind what was a short term racket for the few, and no long term political sustainability once the middle classes started becoming worse off.