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The very best metric is what % of the budget is spent servicing debt, for the US it is around 15%.

On top of that the US government debt is mostly owned by US organizations and citizens; it is assets owned by US taxpayers.

A very different situation from the typical debt/inflationary crisis in developed countries where you have a foreign-owned debt and limited tax base; these cause serious credibility issues for governments, which in turn further push up rates.