"Hi Everyone, POTUS here. About those treasury bonds a lot of you are holding... we're not going to pay interest on them. Or pay back the princiapl. Ever. On a totally unrelated note, here are some pictures of our 11 carrier strike groups. Impressive, aren't they?"
The US would never need to default on its debt, since its debt is in USD. Worst case, it would just print more money, leading to inflation.
If the U.S. decided to completely default on it's debt it would be more destructive to the U.S. economy since the majority of the debt is held by U.S. citizens & institutions. Insurance companies & banks would collapse instantly since the a very large percent of their asset bases would be wiped out.
We (meaning U.S. citizens) owe more to ourselves than to any foreign entity. Default is, at least right now, a political non-starter.
They were the largest military power at the time, Germany in land, British Empire(India,Pakistan, Afghanistan, Ethiopia...) on the sea.
They started getting in debt and a little country called United States became the biggest creditor of the world.
They they killed each other in a stupid war trying to reign supreme, and someone else did.
Now this someone else had started thinking their power will be forever. We will see...