Could $40 Trillion in U.S. Debt Really Blow Up?

With $40 trillion in U.S. debt looming overhead, the question everyone cares about is simple: will it blow up?

First, from a technical perspective, the probability of sovereign default is extremely low

The dollar is the global reserve currency, and the United States can issue debt in its own currency. It has never experienced a sovereign default. The real danger is not a sudden blow-up, but a slow-moving variable: the interest trap.

Consider several turning points and the macroeconomic responses they produced:

The 2008 financial crisis

Large-scale rescue measures and a policy rate cut to nearly zero.

Macroeconomic response: long-term government bond yields collapsed to historic lows, and risk assets fell sharply.

The 2020 pandemic

Enormous fiscal stimulus, with debt increasing by several trillion dollars in a single year.

Macroeconomic response: yields initially surged on supply and inflation expectations, then fell sharply amid zero interest rates and demand for safety.

The 2022–2023 tightening cycle

The policy rate rose from nearly zero to approximately 5%.

Macroeconomic response: bonds fell out of favour, and long-term yields rose to multiyear highs.

The elevated stalemate of 2026

Debt is approaching $40 trillion, while yields remain high.

Macroeconomic response: interest payments have become one of the fastest-growing components of the federal budget, continually squeezing fiscal room.

A blow-up is therefore not the final answer. What matters is the cost of carrying this burden. U.S. debt is high relative to the economy, interest continually eats into the fiscal budget, and long-term yields remain elevated. This describes a prolonged state of strain rather than a sudden collapse.

U.S. debt will not simply blow up. Instead, year after year of high interest rates will continue to squeeze the country's fiscal and policy room. The displaced pressure will not vanish; it will move through three specific channels. Interest payments crowd out federal spending on public services and livelihoods—fiscal substitution. Debt costs are ultimately borne by taxpayers across time—the distribution of the tax burden. High rates encourage greater reliance on short-term refinancing, pushing repayment pressure further into the future—the rolling of the financing structure. This is an important underlying constraint on the U.S. macroeconomy. Inflation, the dollar and fiscal conditions are other structural constraints of this kind, which can be examined individually in future articles.

Data basis: total U.S. public debt, including intragovernmental holdings. The discussion of rates and yields is an overview based on public macroeconomic data.