When he met with reporters in the Oval Office on Friday, President Trump was asked if there was anything Canada, Mexico, or China could do to avert the punitive new tariffs he intended to announce. “No, nothing,” he answered firmly. The impending tariffs were not intended as a negotiating tool, he avowed. “We’re not looking for a concession.”

The next day, Trump signed executive orders imposing tariffs of 25 percent on goods imported from Mexico and Canada, and an additional 10 percent tariff on imports from China. But the new levies on America’s neighbors, which were to take effect on Tuesday, were suspended Monday after Mexico’s president and Canada’s prime minister placated Trump with modest gestures, agreeing to post more troops along their US borders to interdict drug traffickers.

Trump declared victory, pronounced himself “very pleased,” basked in the adulation of his devotees, and didn’t unleash the sweeping trade war that had caused markets to plunge in fear.

Apparently he had been looking for a concession.

But to what end?

Karoline Leavitt, the White House press secretary, said this week that Trump has been “astoundingly clear” about what he expects tariffs to accomplish. In reality, he has been anything but. Trump’s support for tariffs hasn’t wavered since the 1980s. But even now no one can say with certainty what he wants them to achieve.

According to his press secretary, the purpose of Trump’s tariffs is to stop “the illegal surge of deadly drugs and of human beings that we have seen trafficked over the southern border.” But the president or his top aides have also claimed at various times that tariffs will coerce other countries to pay “their fair share.” Or they will strengthen national security. Or create American jobs. Or put a stop to unfair trade practices. Or render the federal income tax unnecessary. Or pressure Canada to become “our Cherished 51st State.” Or force Denmark to sell Greenland to the United States. Or compel Mexico to pay for a border wall. Or put an end to the United States being “ripped off by other countries.”

In Trump’s view, the purpose of tariffs can be as harsh and focused as intimidating the government of Colombia into accepting deported migrants. Or it can be as broad and uplifting as American patriotism, since, in his words, “anybody that loves and believes in the United States” is in favor of higher tariffs.

Abraham Lincoln once said that he had “never had a feeling politically that did not spring from the sentiments embodied in the Declaration of Independence.” Trump, it would appear, has never had a feeling politically that did not spring from the view that America’s trading partners deserve to be punished with import duties. The specific reason is secondary. For Trump, tariffs have never been a means to an end; they are an end in themselves.

So don’t expect the truce in Trump’s North American trade war to last. Sooner or later, the president — who has long preached that “trade wars are good and easy to win” and that tariff is “the most beautiful word in the dictionary” — will again be demanding higher taxes on imports.

Like most people with an obsession, Trump’s protectionism is impervious to logic. That is why he can simultaneously claim that “the tariffs are going to make us very rich and very strong” and “cost Americans nothing” — then turn around and concede, as he did on Sunday, that Americans would feel “some pain” from new tariffs. It is why he could boast that the US-Mexico-Canada Agreement, which he signed in 2020, was “the largest, most significant, modern, and balanced trade agreement in history” — yet insist now that tariffs are needed to stop the United States from being victimized by “soft and pathetically weak Trade agreements.”

Trump’s experience with tariffs in his first term should have taught him how counterproductive they are. The trade war he launched against China beginning in 2018 saddled American households with higher prices. The US trade deficit, which Trump was certain he could shrink, grew bigger than ever. Chinese exports, which had been declining before Trump took office, surged after he became president. And the growth Trump promised in US manufacturing jobs and production failed to materialize.

In his inaugural address last month, the 47th president invoked the legacy of the 25th as proof that ultra-hawkish trade policies work. “President McKinley made our country very rich through tariffs,” Trump said. In fact, McKinley’s tariffs were highly unpopular — so much so that he himself abandoned his protectionist policy.

Trump’s tariff policies proved a dud the first time he was in the White House. They will fare no better this time. If he really wanted to emulate the predecessor he idolizes, Trump would learn from experience and change his approach. But this president is no McKinley. More’s the pity.