MEXICO CITY — As President Trump announces that painful tariffs on Canada and Mexico are a fait accompli that will take effect Tuesday, Mexicans are wondering what additional concessions President Sheinbaum could offer to appease America’s commander-in-chief. 

America will impose tariffs, “25 percent on Canada and 25 percent on Mexico, and that’ll start” on Tuesday, Mr. Trump said Monday afternoon, ending days of speculation that started after he delayed the measure earlier in his presidency. “They’re going to have to have a tariff, so what they have to do is build their car plants, frankly, and other things in the United States in which case they have no tariffs.”

Earlier in the day, Mexico City tongues were speculating that the president might target only some of the country’s business sectors. Others said the tariffs might go as low as 10 percent. Yet even if that were the case, Mr. Trump’s mere threat and his unpredictable governing style are taking a toll on the Mexican economy even before the tariffs kick in. 

Economic growth has already slowed to a trickle, the president of the Mexico City-based consultant firm Rozental and Associates, Andres Rozental, tells the Sun. Now, he adds, “if there are any tariffs, any tariffs at all, in addition to the ones that may already be in force, like we have already from the first Trump administration on steel and aluminum, that’s going to have a tremendously negative effect on the economy.”

Tariffs, and their threat, Mr. Rozental says, are harmful “not only because we’re not going to be able to perhaps export as much as we have been exporting of manufacturers to the U.S., but also because it will be a death knell for  investors and for potential new projects. People will say, ‘Well, today it’s this but tomorrow it may be that.’” Businesses don’t like to be subjected to such uncertainty, “and so they’ll go elsewhere.”

In the latest harbingers of exodus from Mexico, the Japanese car conglomerate Honda now intends to produce its next-generation Civic hybrid in Indiana, rather than Mexico as originally planned. The decision was made “to avoid potential tariffs,” Reuters reported Monday from Japan. 

Speaking with reporters Monday, Mr. Trump insisted he has good rapport with Ms. Sheinbaum. “I have a lot of respect for her,” he said. The president “knows they’ve done a good job on the border,” his secretary of commerce, Howard Lutnick, told CNN earlier, speaking of the Mexican government. Yet, he added, “they haven’t done enough on fentanyl.” 

In a sharp departure from the policies of Ms. Sheinbaum’s predecessor and mentor, President Lopez-Obrador, Mexico has pledged to put 10,000 troops to the border, where a migration flood has abated significantly since Mr. Trump took office. Ms. Sheinbaum also dispatched troops to the country’s southern border, to combat caravans coming into Mexico from Central America and elsewhere on the way to America. 

In another gesture to Washington, Ms. Sheinbaum announced a 10 percent tariff on products from Communist China, matching tariffs Mr. Trump had announced earlier, to which he added another 10 percent Tuesday.

“I think it would be a nice gesture if the Canadians did it also, so in a way we could have a ‘fortress North America’ from the flood of Chinese imports coming out of the most unbalanced economy in history,” the treasury secretary, Scott Bassent, told Bloomberg over the weekend. 

In another departure from past policies, Mexico last week extradited 29 cartel kingpins to stand trial in America. While several of the men were of an older generation and semi-retried, some were active in the crime arena. While the extraditions are debated at Mexico City, violence in places like Culliacan and other parts of Sinaloa state is only rising.     

“Every time they bust a big cartel guy, we suffer,” a Sinaloa official told the Sun a few years ago. After the kingpins are paraded for the cameras, he explained, lower-ranked criminals battle in the streets to take their places. “We don’t have the wherewithal to calm the war down,” he said. 

Following last week’s extradition of a Sinaloa cartel co-founder, Ismael “El Mayo” Zambada, violence at the city of Culliacan has risen sharply, as residents fear going outside at night. Over the weekend a band, Grupo Firme, canceled a show at another Sinaloa city, Matatzlan, after receiving a threat that was delivered on a severed head. 

“I don’t think she had a choice,” Mr. Rozental said of the Mexican president’s decisions to appease Mr. Trump. Yet, Mexicans are now wondering if that was enough, and what else they can do to eventually reverse the devastating tariffs that promise to wreak havoc on their economy.