A U.S. ‘debt spiral’ could start in coming years when the interest rate on government borrowing exceeds economic growth, budget watchdog says

Total federal debt is nearing an ominous milestone in a few years, but a potentially more troubling tipping point could also arrive soon.

According to the latest projections from the Congressional Budget Office, publicly held debt is currently at $31 trillion and is about 100% of GDP. By fiscal year 2030, debt is expected to exceed the 106% record set after World War II, then surge to 120% by 2036.

Fueling that accumulation are annual debt interest costs, which will more than...