When interest on national debt overtook military spending, it triggered a limit where the U.S. may ‘cease to be a great power’, warns Hoover historian

Interest payments on the U.S. national debt are set to surpass $1 trillion in 2026, some $88 billion a month—equal to spending on defense and education combined. The economy has tripped past this point before: that is, there have been brief periods in history when service payments on the debt have outweighed military spending, for example, in the post-war 1920s.These stints have either been relatively short-lived or have not occurred in an established, advanced economy. But in 2024, under the Biden administration, the U.S. Treasury passed that threshold again, the first sustained period in recent memory where debt interest payments have outweighed military spending. Both the Republicans and Democrats have added trillions to the debt burden, though with President Trump now back in the Oval Office, pressure falls on him to address the issue.

An excess of debt over defense is a violation of Ferguson’s Law, as described by Hoover economic historian Sir Niall Ferguson in a working paper published earlier this year. Ferguson’s Law states that “any great power that spends more on debt servicing than on defense risks ceasing to be a great power.”

“This is because the debt burden draws scarce resources towards itself, reducing the amount available........

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