The U.S. national debt has surpassed 100% of gross domestic product, a threshold that has not been crossed since the end of World War II.

Data from the Bureau of Economic Analysis shows national debt reaching 100.2% of GDP on Thursday, and that debt held by the public on March 31 was $31.27 trillion.

Nominal GDP was estimated at $31.22 trillion for the 12-month period ending in March.

"It's happened — the national debt is now larger than the U.S. economy, about twice the historic average," Marc Goldwein, senior vice president of the Committee for a Responsible Federal Budget, said in a statement.

"We've heard plenty of alarm bells in the past few years about our fiscal path, but this one rings especially loudly. The real question is whether or not our leaders in Washington will listen," he added.

The current debt-to-GDP ratio of 100.2% is "uncharted territory" and a "scary place to be," Goldwein told The Wall Street Journal.

"The higher we allow our debt to grow, the more we erode our own prosperity and that of future generations," Goldwein said in his statement.

"Rising debt compromises affordability by slowing income growth, pushing up interest rates, and increasing inflationary pressures. Debt squeezes our budgets with massive interest costs."

Goldwein added that rising debt exposes the U.S. "to challenges from geopolitical rivals" and will require "corrective action." Otherwise, it could kick off a "devastating" fiscal crisis, he said.

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