>>509248087it's complicated.
Normally, when a country borrows money, it's borrowing from an external entity. For example, in gold based exchanges, you'd make an IOU note to someone who had the gold. This changes to banknotes once gold became obsolete, and the issuing entity became banking systems.
The united states government doesn't do this. The current global currency is USD, and the issuing authority of the USD is...the US government. So the US government is really just borrowing against itself (which is where the "money printer goes BRRRRRRRRRR" concept comes from). The head of the federal reserve is appointed by the US government (with approval from executive and legislative branches), and obama was even floating the idea of forging a trillion dollar platinum coin (it must sound stupid but it almost happened - after all what's one coin going to do against 40 trillions of debt? dumb fucking ni-)