Facing the threat of tariffs from President Trump after he took office, Mexico bent over backward to comply with his demands.

Almost immediately, the government moved to secure its northern border, severely stanching migration to the United States. Then it hunted cartel leaders in a dangerous fentanyl stronghold. And just last week, in a once-in-a-generation move, it delivered into U.S. custody 29 of the country’s most powerful drug lords.

But even after all of that, Mr. Trump imposed the tariffs anyway, shaking global markets. The move left officials in both countries baffled about what the White House was trying to accomplish and frantically asking the same question: What was Mr. Trump’s endgame?

Even some people close to the president seem to disagree on the answer.

Some outside advisers predict that the tariffs, which are currently at 25 percent on most imports from Mexico and Canada, will result in a steady stream of revenue for the United States.

Others maintain that they are Mr. Trump’s attempt to shake up the global order and flex his muscles on the world stage.

Many believe that the president, who has seen trade deficits as a crisis for decades, is simply trying to follow through on a threat that he has dangled over Mexico for months. By pressing forward, they say, Mr. Trump is seeking to ensure that he is seen as tough among world leaders as he pushes his foreign policy agenda in other global hot spots, including Gaza and Ukraine.

Mr. Trump had initially announced the tariffs shortly after taking office. But he delayed their imposition right before they were to take effect in early February, after speaking with President Claudia Sheinbaum of Mexico and Prime Minister Justin Trudeau of Canada. He gave them about another 30 days to show results.

On Monday, the White House said that the tariffs were going forward because both Mexico and Canada had “failed to adequately address” the flow of drugs into the United States, noting that the cartels have “an intolerable relationship with the government of Mexico.”

That statement prompted some experts in Mexico to theorize that perhaps Mr. Trump wanted Mexico to go harder after politicians accused of corruption.

“Trump keeps insisting on this point, and Sheinbaum has done absolutely nothing on those links,” said Eduardo Guerrero, a security analyst based in Mexico City.

Still, there was little more to go on than theories at this stage. And regardless of what Mr. Trump’s actual motivations might be, his decisions have resulted in a state of confusion and frustration on both sides of the border.

Two Mexican officials said that they had reached a limit on what they were able to offer in an effort to avoid the tariffs, and that it was unclear what more Mexico could have done on security. They cautioned, though, that they still had very little understanding of what else Mr. Trump might want.

Mr. Trump’s moves have also bewildered some American officials who have worked for years on issues related to drug cartels. They expressed concern that without a clear path forward, the tariffs could jeopardize any future security cooperation with Mexico, according to two people familiar with the matter.

Even some within the Trump administration recognized that the imposition of the tariffs may have finally exhausted the Mexican government’s willingness to work with the United States and that the country may have little additional capacity to deliver further wins.

But even though there was some internal pushback about the tariffs, Mr. Trump’s advisers no longer voice the sort of robust disagreement on what he wants that they did during his first term.

The puzzlement about the tariffs was being felt even after high-level meetings last week in Washington between a delegation from Mexico and senior U.S. officials to hammer out a security agreement between the two countries.

The goal of the talks from the Mexican perspective was to avoid the tariffs altogether by reaffirming Mexico’s desire to work in concert with the United States on cracking down on the cartels and stemming the flow of illicit drugs across the border.

U.S. officials used the talks as the backdrop to reveal a secretive but spectacular development they hoped would appeal to Mr. Trump. Just before the delegation left Washington, Mexican officials announced that they were delivering into U.S. custody dozens of cartel leaders and were even speeding up the process of turning them over by skirting their country’s normal extradition laws.

That move, lauded as a win for Mr. Trump, was widely viewed as one of the most important efforts by Mexico in decades to send drug traffickers to face charges in American federal courts. While the deal was based on negotiations that had started during the last administration, it was hastily concluded by diplomats and law enforcement officials in time to be ready for the meetings last week, according to the people familiar with the matter.

Those expelled from Mexico were some of the most powerful and violent cartel leaders in the country’s history.

Among them was Rafael Caro Quintero, a Sinaloa cartel figure who masterminded the torture and murder of Enrique Camarena, an agent for the U.S. Drug Enforcement Administration who was working under cover in Guadalajara in 1985.

Mexico also released into American hands Miguel Ángel Treviño Morales, a former leader of the Zetas cartel, which helped perfect the practice of using carnage as a message.

The handovers were just one in a series of concessions by Mexico.

Since Mr. Trump first started floating the idea of tariffs in November, the Mexican government has intensified its military crackdown in Sinaloa state, a major hub of fentanyl production. The region is the home base of the Sinaloa cartel, which the U.S. government blames for much of the synthetic opioids flooding over the border.

A slew of arrests, drug lab raids and fentanyl seizures have struck at the core of cartel operations in Culiacán, the state capital of Sinaloa, prompting some producers to shut down manufacturing of the drug altogether, according to interviews with six cartel operatives.

Ms. Sheinbaum announced the deployment of 10,000 National Guard troops at the border in early February, and the government has ratcheted up enforcement has contributed to a plunge in illegal crossings into the country. Kristi Noem, the homeland security secretary, announced last week that only 200 people had been apprehended at the southern border one Saturday in February, which she said was the lowest daily figure in more than 15 years.

The tariff announcement on Monday was met with shock in Mexico, but experts said it was unlikely that even after what was seen as unfair punishment, Ms. Sheinbaum would shut down collaboration on security issues. The risks, they said, were simply too high.

“While she’s a very nationalist and leftist woman, she’s also very pragmatic in terms of her relationship with the U.S.,” Mr. Guerrero said. “If that relationship goes badly, it would be a disaster for her government.”