It's easy, really. Take China, until around 2018 it bent over backwards to deliver ever cheaper good to the West. The rich of China are now worried about the indebted masses surrounding them. This is the same for the U.S. It isn't the debt per se that causes wars; it's the humiliation, furstration, anger, fear, etc., that it causes. If the economy can't be revved up again (some new exciting invention?) then countries will fight about how sets prices, which is part of what's going on in Ukraine.

Foreign debt servicing was a major component behind Hitler's rise.

I believe it 50/50 the U.S. gets directly involved, in the future. Russia or China. Perhaps both. The U.S. is THAT arrogant ;)