The U.S. raises money by selling bonds. These bonds have low low low interest rates.
For example they sell 1 bond to China for 1 million dollars that they will pay back with a low interest rate in 20 years. 20 years comes around and they pay China 1.1 million dollars back for that bond.
These are set payments which is why China just can’t “call in their debt” whenever they want. And also why the deficit is much more important then the actual debt.
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