[dmm]

The US treasury is currently borrowing at the lowest rates in 70 years. To obtain the lowest rates possible, about half of the US debt is in bonds that mature in less than a year. This means huge quantities of bonds are constantly maturing and being resold. Any change in interest rates will quickly result in much higher interest payments.

These rates are so low because the fed is buying the bonds and treasuries are currently the safest place to park huge amounts of cash. The rates even go negative at times because US bonds are are safe place for cash. If the treasury starts defaulting on its debts, that will change very quickly. Not only that but the status of the USD will change very quickly.