I haven't run the numbers, but cost of servicing the debt will depend on the structure of debt issued. A 30y treasury doesn't need to be refinanced/paid back f

I haven't run the numbers, but cost of servicing the debt will depend on the structure of debt issued. A 30y treasury doesn't need to be refinanced/paid back for 30 years, 10y for 10 years etc. A smart Treasury would have locked in a lot of the debt in longer dated treasuries back when they were yielding 1% or less. This would have made the debt payments largely fixed, regardless of Fed hikes. Unfortunately from what I've heard, they are mostly financing through the fed funds/overnight rate. So yes, US debt service costs are more variable than they could have been. But maybe somebody can chime in with hard numbers