President Trump’s bully-ball trade tactics are built on his belief that other countries need us more than we need them. Americans are the world’s biggest shoppers, and Trump is betting that stores need customers more than customers need any particular store.

But in one important respect, the United States is the store that needs customers. The government is heavily reliant on foreign buyers of federal debt. Between 2021 and 2023, 45 percent of the increase in federal borrowing was drawn from foreign pockets, and most of that money came from private investors, not other governments.

People in countries targeted by Trump’s tariffs already are boycotting made-in-America products like Teslas and Tennessee whiskey. If they sour on Treasuries, too, Americans will feel the pain. When demand for Treasuries weakens, the government has to pay higher interest rates to woo investors, leaving less money for everything else.

Trump is angering the rest of the world even as the United States needs its money more than ever. Federal spending is on the rise despite Trump’s decimations of the federal work force, and projected revenues will take a big hit if Republicans extend Trump’s 2017 tax cuts. The federal debt, measured as a share of national economic output, is on track to surpass the record levels of World War II. And European countries, led by Germany, are increasing their borrowing, intensifying competition for investment.

The popularity of Treasuries will not be shaken easily. They are readily available, widely regarded as safe and woven into the fabric of the global financial system. When Trump vaguely suggested in early February that the government might not pay all of its debts, markets ignored him. So far bond investors are treating Trump’s return to power with much greater equanimity than investors in stocks. There is no sign the government is paying an interest rate premium for the president’s behavior.

But small risks demand attention when the potential consequences are big enough. An increase of even 0.1 percentage points in the average interest rate on federal debt would cost more than $300 billion over the next decade, according to the Congressional Budget Office.

It’s often said that presidents have limited power over the economy, but it’s more accurate to say that they have limited power to increase growth.

They have a lot more power to break things.