In March 2018, a day after asserting sweeping tariffs on metals imported from America’s allies and adversaries alike, President Donald J. Trump took to social media to share one in every of his central financial philosophies: “Commerce wars are good, and straightforward to win.”

As president, Mr. Trump presided over the most important improve in U.S. tariffs for the reason that Nice Melancholy, hitting China, Canada, the European Union, Mexico, India and different governments with stiff levies. They hit again, imposing tariffs on American soybeans, whiskey, orange juice and bikes. U.S. agricultural exports plummeted, prompting Mr. Trump to ship $23 billion to farmers to assist offset losses.

Now, as he runs for president once more, Mr. Trump is promising to ratchet up his commerce warfare to a a lot larger diploma. He has proposed “common baseline tariffs on most overseas merchandise,” together with larger levies on sure nations that devalue their forex. In interviews, he has floated plans for a 10 percent tariff on most imports and a tariff of 60 percent or more on Chinese language items. He has additionally posited chopping the federal revenue tax and counting on tariffs for income as a substitute.

Mr. Trump, who as soon as proclaimed himself “Tariff Man,” has lengthy argued that tariffs would increase American factories, finish the hole between what America imported and what it exported and improve American jobs.

His first spherical of levies hit greater than $400 billion value of imports, together with metal, photo voltaic panels, washing machines and Chinese language items like sensible watches, chemical substances, bicycle helmets and motors. His rationale was that import taxes would revive American manufacturing, cut back reliance on overseas items and permit U.S. corporations to higher compete in opposition to low cost merchandise from China and different nations.

Economists say the tariffs did cut back imports and inspired U.S. manufacturing unit manufacturing for sure industries, together with metal, semiconductors and laptop gear. However that got here at a really excessive price, one which probably offset any total good points. Research present that the tariffs resulted in higher prices for American customers and factories that depend upon overseas inputs, and reduced U.S. exports for sure items that have been topic to retaliation.

Mr. Trump is now envisioning taxing maybe 10 instances as many imports as he did throughout his first time period, an method that economists say might set off a commerce warfare that drives up already excessive costs and plunges the U.S. right into a recession.

David Autor, an economics professor on the Massachusetts Institute of Expertise, stated the proposals would have “a really massive impact on costs virtually instantly.”

“I don’t suppose they’ll do it,” Mr. Autor stated. “It might simply trigger a recession.”

In a latest letter, 16 Nobel Prize-winning economists wrote that they have been “deeply involved” in regards to the dangers a second Trump administration posed to the financial system, inflation and the rule of regulation.

“We consider {that a} second Trump time period would have a damaging affect on the U.S.’s financial standing on the earth and a destabilizing impact on the U.S.’s home financial system,” they wrote.

Mr. Trump and his supporters have a way more constructive view of tariffs, arguing that they function leverage with overseas governments, cut back the trade deficit with China and consequence within the progress of U.S. manufacturing jobs.

“I occur to be a giant believer in tariffs as a result of I feel tariffs provide you with two issues: They provide you financial achieve, however additionally they provide you with political achieve,” Mr. Trump stated on a recent podcast.

Karoline Leavitt, the Trump marketing campaign nationwide press secretary, stated in a press release that “the American folks don’t want nugatory out-of-touch Nobel Prize winners to inform them which president put extra money of their pockets.”

“President Trump constructed the strongest financial system in American historical past,” she stated. “In simply three years, Joe Biden’s out-of-control spending created the worst inflation disaster in generations.”

Jamieson L. Greer, a accomplice within the worldwide commerce crew at King & Spalding, who was concerned with China commerce negotiations throughout the Trump administration, stated the view of Trump officers was that tariffs “will help help U.S. manufacturing jobs particularly, particularly to the extent that they’re remediating an unfair commerce apply.”

China has lengthy engaged in insurance policies that drawback American staff, however different nations even have unfair commerce and tax insurance policies or misaligned currencies, Mr. Greer stated.

“Should you degree out that taking part in area, it makes it in order that Individuals don’t need to compete unfairly,” he stated.

Mr. Trump’s tariffs have home supporters among the many industries which have benefited from them. And President Biden gave them his personal stamp of approval by selecting to keep Mr. Trump’s China tariffs in place whereas including a few of his personal, together with on electrical vehicles, metal and semiconductors.

However among the industries that have been hit hardest by Mr. Trump’s commerce wars will not be wanting ahead to a sequel. Executives in sectors like retail and spirits fear that one other spherical of tariffs might reignite tensions, elevate their prices and once more shut off vital markets overseas.

Spirit exports to Europe declined by 20 % after the European Union imposed a 25 % retaliatory tariff on American whiskey in response to the Trump administration’s tariffs on metal and aluminum. And the China tariffs elevated the costs that retailers needed to pay for his or her merchandise, forcing them to both elevate costs for his or her prospects or reduce into their income.

“We’d like a commerce coverage, not simply extra tariffs,” stated David French, government vp of presidency relations on the Nationwide Retail Federation. His group, which represents malls, e-commerce websites and grocers, ran a tv advert marketing campaign opposing the Trump tariffs in 2018. “All they’ve carried out is add friction to the provision chain and price customers $220 billion.”

“Former President Trump appears to be like at commerce as some kind of zero-sum recreation — for those who win, I lose and vice versa,” Mr. French stated. “That’s actually not the way in which commerce works.”

The facility of tariffs to assist or hinder exports is evident in industries that ultimately gained a reprieve. In 2021, whiskey tariffs have been briefly suspended as a part of a deal the Biden administration made with the European Union. American whiskey exports to the bloc rose from $439 million in 2021 to $705 million final yr.

Chris Swonger, the chief government of the Distilled Spirits Council of america, stated he was hopeful that, if re-elected, Mr. Trump would respect that sturdy exports of American spirits would assist obtain his purpose of lowering the commerce deficit. The lobbying group desires the E.U. tariff suspension, which expires subsequent March, to be prolonged.

“For President Trump, clearly we respect and respect his efforts to cut back the commerce deficit,” stated Mr. Swonger, who has made his case to Trump marketing campaign officers. “Imposing tariffs on distilled spirits can be counter to lowering the commerce deficit.”

Analysis suggests the tariffs did accomplish their purpose of accelerating home manufacturing within the industries they protected, however did so by imposing different prices on the U.S. financial system.

One nonpartisan government study discovered that the tariffs on overseas metal and aluminum elevated U.S. manufacturing of these metals by $2.2 billion in 2021. However American factories that use metal and aluminum to make different issues, like vehicles, tin cans and home equipment, needed to pay larger prices for his or her supplies, and that diminished the output of these factories by $3.5 billion in the identical yr.

Research counsel the tariffs additionally had a blended report when it got here to jobs. In a latest paper, Mr. Autor and different economists discovered that the cumulative impact of Mr. Trump’s commerce insurance policies and different nations’ retaliation was slightly negative for American jobs, or at finest a wash.

By way of inflation, studies have estimated that American households confronted larger costs because of the tariffs — from a number of hundred {dollars} to greater than $1,000 yearly.

However economists say customers in all probability didn’t affiliate the upper costs they paid with the tariffs, provided that inflation was low all through Mr. Trump’s tenure and the financial system was sturdy.

Whereas the financial system stays strong, costs have spiked since 2021, and inflation stays elevated. That might make tariff-induced value will increase extra apparent and extra painful this time round.

A recent analysis by the Peterson Institute of Worldwide Economics discovered that if Mr. Trump did impose a ten % tariff on all items and a 60 % tariff on China, it could price a typical family in the course of the revenue distribution about $1,700 in elevated bills annually.

One other evaluation, by the right-leaning American Motion Discussion board, estimated {that a} 10 % tariff might impose extra annual prices of as much as $2,350 per American family. Including a 60 % tariff on China would add one other $1,950 to U.S. family prices.

The burden of these tariffs would fall extra closely on poorer households, as a result of they spend a bigger share of their revenue on on a regular basis merchandise.

That might finally backfire on Mr. Trump, provided that voter considerations about inflation are high of thoughts.

As he waited in line to attend Mr. Trump’s rally on Saturday in Philadelphia, Paul Rozick, {an electrical} warehouse supervisor from Bensalem, Pa., stated excessive grocery and fuel costs had outpaced his pay raises.

“Inflation goes up like 20 %, however our paychecks go up like 2 %,” Mr. Rozick stated. “I’ve acquired much less cash within the financial institution as a result of I’m spending extra money once I stroll out the door.”