The government of Ireland can run out of Euros-they make Euros in Frankfurt. And the government of Peru can run out of dollars-they make dollars in Washington. But the government of the United States can’t run out of dollars. The problem we could find ourselves with is the problem of inflation. Problematic inflation is a genuinely problematic thing, but it’s a strange thing to worry about at the moment when inflation’s been running unusually low for years. Our current problem is that the total volume of nominal spending is way too low, which means that as a country we’re producing much less than we could be.

From Yglesias