Here's a scary thought: what if one day, the U.S. government tries to sell its bonds and... nobody really wants to buy them? That's the "vicious" scenario former Treasury Secretary Henry Paulson is urging Washington to prepare for right now.

Paulson, who famously steered the Treasury through the 2008 financial crisis, said on Thursday that U.S. authorities need to draft a contingency plan for a potential collapse in demand for government bonds—before it's too late.

"We need an emergency break-the-glass plan, which is targeted and short-term, on the shelf, so it's ready to go when we hit the wall," Paulson said during an interview on Bloomberg Television's Wall Street Week with David Westin.

A Different Kind of Monster

If you're thinking, "Well, he handled 2008, how bad could it be?" Paulson has a clear answer: much, much worse.

He explained that a U.S. debt crisis would be far harder to contain than the credit meltdown he managed back then. The problem isn't just banks failing; it's the foundation of government financing crumbling.

"When you hit the wall and you're trying to issue Treasuries and the Fed is the only buyer and the prices of the Treasuries are going down and interest rates are up, that's a dangerous thing," he said.

Think about that chain reaction. If demand for U.S. debt dries up, the Treasury has to offer higher interest rates to attract buyers. Those higher rates ripple through the entire economy, making everything from mortgages to business loans more expensive. And if the Federal Reserve ends up as the "only buyer," that's essentially a crisis of confidence in the U.S. government's credit.

Paulson admits the timing of such a doomsday scenario is impossible to predict. But he's certain about the impact: "When we hit it, it will be vicious, so we have to prepare for that eventuality."

The Global Pressure Cooker

Paulson's stark warning isn't happening in a vacuum. It lands as fiscal pressure mounts worldwide.

The International Monetary Fund has separately warned that the ongoing Middle East conflict is acting as a "large, sudden tax on income" for fuel-importing economies. That pushes prices higher and slows growth—strains that could accelerate pressure on sovereign debt markets everywhere.

Back home, the numbers are eye-watering. U.S. national debt has surpassed $39 trillion. The deficit is running at roughly 6% of GDP—a level historically seen only during major wars or deep recessions. The Congressional Budget Office projects the debt-to-GDP ratio will hit a record 108% by 2030.

So, what's the fix? According to Paulson, it's the classic, politically toxic combo: higher revenues, closing tax loopholes, and overhauling big-ticket entitlement programs like Social Security and Medicare.

The real problem, he notes, isn't finding the policy solutions. It's the politics. "Congress doesn't like to do unpleasant things until there is an immediate crisis," Paulson said.

In other words, by the time everyone agrees we have a problem, we might already be hitting that wall. And as Paulson reminds us, that's when things get vicious.