WASHINGTON — President Donald Trump claimed Wednesday that sky-high new taxes on imported goods would be “reciprocal,” meaning they were payback for tariffs other countries have slapped on U.S. exports.

But the reciprocal tariffs turned out not to be based on actual levies imposed by other countries. Instead, they’re based on a formula made up by the White House ― and widely mocked by experts.

Douglas Holtz-Eakin, a conservative economist American Action Forum and former director of the Congressional Budget Office, called it “malpractice” in response to another conservative economist who called it “embarrassing.”

The formula, which resulted in wildly different tariffs for various foreign countries, including several uninhabited islands, first came to wide attention thanks partly to analysis by an anonymous social media user who reckoned the percentage rate of the tariffs matched other countries’ trade surpluses with the U.S. divided by their exports. The journalist James Surowiecki also noticed the correlation.

“They didn’t actually calculate tariff rates + non-tariff barriers, as they say they did,” Surowiecki wrote. “Instead, for every country, they just took our trade deficit with that country and divided it by the country’s exports to us.”

In other words, the supposedly reciprocal tariffs, which are supposed to combat arbitrary foreign barriers to U.S. goods, are themselves based on an arbitrary formula.

In a response on X, the website formerly known as Twitter, White House spokesman Kush Desai called the analyses “incorrect” and pointed to a fuller explanation of the formula from the U.S. Trade Representative, which claimed that other countries’ “non-tariff policies” cause them to sell more goods to the U.S. than we sell back to them.

“If trade deficits are persistent because of tariff and non-tariff policies and fundamentals, then the tariff rate consistent with offsetting these policies and fundamentals is reciprocal and fair,” the USTR said on its website, which included a seemingly more complicated math equation and several academic citations.

Alan Cole, an economist with the Tax Foundation, said he suspected Desai didn’t really understand the equation.

“So they thought, ‘Our thing is more complicated and smarter-looking than that. It has more fancy Greek letters. It can’t possibly just be a very, very simple division,’” Cole told HuffPost. “After you cancel it out, it’s the same formula.”

Still, Trump has long claimed that trade deficits are inherently bad, and the formula could be said to reflect his zero-sum view of global trade, in which U.S. consumers are getting ripped off if they spend more on products from abroad than people in foreign countries spend on goods made in the U.S.

“Our country has been looted, pillaged, raped and plundered by nations near and far, both friend and foe alike,” Trump said Wednesday.

Trump has talked about using tariffs as leverage against Canada, Mexico and China to stop the flow of fentanyl into the U.S., and he’s said the U.S. would be better off if Americans made more of their own products. He’s also said tariffs should be a more significant source of revenue for the U.S. government.

Cole noted that the U.S. purchases a lot of consumer goods that are made more cheaply in other countries and that the outgoing dollars are often reinvested in American companies and government debt, rather than simply hoarded by foreigners. He questioned the wisdom of trying to upend the global order by making it more expensive for Americans to buy clothing and electronics made in Indonesia, for example.

“The U.S. is this hub for all sorts of investment, and people love our financial assets, and they have to give us goods in exchange, and that’s kind of how the world’s been working for a long time, and that’s why we’ve run a trade deficit,” he said. “Why should Americans be sewing shirts together, for example? A huge fraction of these tariffs are based on bilateral trade imbalances with Southeast Asia, where they’re good at making textiles.”

Since the tariffs are paid by U.S. importers who can raise prices to recoup all or part of the cost of the tariffs, Trump’s “liberation day” announcement this week could be tantamount to the largest tax increase on U.S. consumers in decades. At the same time, economists have said the tariffs could increase price inflation and slow economic growth, potentially even throwing it in reverse and triggering a recession.

“This has to be one of the biggest unforced economic policy errors in US history,” wrote David Beckworth, an economist with the Mercatus Center, a right-leaning think tank.

The Nobel-Prize-winning liberal economist Paul Krugman called the crudity of the “reciprocal” tariffs formula shocking.

“When the fate of the world economy is on the line, the malignant stupidity of the policy process is arguably as important as the policies themselves,” Krugman wrote. “How can anyone, whether they’re businesspeople or foreign governments, trust anything coming out of an administration that behaves like this?”

Another explanation for the tariffs is that Trump is simply using a power that Congress has delegated to the White House and nobody can stop him.

“Tariffs are a tool the president enjoys because it’s personal power,” Rep. Ryan Zinke (R-Mont.), who served as interior decretary during the first Trump administration, told HuffPost this week. “It’s personal ― he doesn’t have to go through Congress. He can exercise personal power.”