People like to bring up places like Argentina and Venezuela, but their debts weren't denominated in their own currencies, so they had to collect dollars in order to repay debts in dollars. As a currency issuer, since we create dollars, we can never run out of them. Nor do we have to round up dollars and take them back from currency holders before we can repay a debt. Doing so just takes those dollars away from the non-government so that the issuer can zero out a ledger somewhere. The interest is interest we choose to pay, for some reason. The only way we could default on our debt is if we decide to. The only way to "pay off" the "debt" is to take all the dollars away from the non-government, which is _us_.