I bought, and yet to fully read, "Debt - The first 5000 years". One of the things the book states at the start is what you are saying: Not every debt has to be paid off. One of the risks creditors take is the possibility of having a debt not paid back.
I also remember how Haiti was, to this day, punished via monetary means. Haiti wanted freedom? Fine... they will (and did) cripple the entire country.
Another example from the book: Madagascar. The French invaded, and took out their Queen. Then imposed taxes on the population as to get back the money they invested in the invasion/war. wtf