https://realmoney.thestreet.com/articles/10/25/2016/national...
Also bear in mind a lot of that debt is held by Americans...
In any case a fundamental problem is that we have rather more debt than we have any feasible way to pay. A very large part of that debt is held in the form of Treasury bonds issued to Social Security. Which leads to Social Security being financially solvent on paper for many decades to come. In fact it looks like once the Baby Boom retires, either Social Security is solvent or the US government is solvent, but not both.
This is wrong since it doesn't take into account other governments and entities outside of the US that hold treasury securities.
That's the harbinger of doom, when treasury bond rates start to act weird, no one knows what level of debt that will happen at so the hand wringing over X trillions is kind of silly.