GUATEMALA CITY — The tears that migrants tried to cover with their shirts as they stepped off the plane that had deported them from the United States turned to smiles and applause as they were welcomed home, and told how crucial they are to Guatemala’s growth.
But Kevin K. McAleenan, the acting secretary for the Department of Homeland Security, looked concerned. At the end of his first visit to Guatemala as the head of the primary American immigration agency, the scene provided evidence that efforts to keep families from making the dangerous journey to the United States border were not working.
“Our neighbors have been our friends, and I can offer you our full support,” Mr. McAleenan told leaders of El Salvador, Honduras and Guatemala a few days earlier. He also pledged to look into restoring to the region American aid that the administration cut this year, and signed a two-year agreement to send up to 80 homeland security agents to Guatemala to help train the local authorities and stop human trafficking rings.
President Trump announced a harsher approach on the same day that Mr. McAleenan left Guatemala City. Unless Mexico did more to stop the flow of migrants headed north from Guatemala’s border, Mr. Trump said, the United States would impose a 5 percent tariff on all Mexican imports.
More Guatemalans than migrants from any other country — and many of them traveling in families — are seeking to enter the United States along its southwestern border. In April, a majority of 109,144 migrants who were stopped at the border — the highest monthly total since 2007 — were from Guatemala. The increasing flow of migrants has overwhelmed American immigration facilities, where more than 80,000 people are being held.
Situated directly south of Mexico, Guatemala is also a crucial transit point for migrants headed to the United States from Honduras or El Salvador. Most people leaving the region are hoping to unite with relatives already in the United States, searching for economic opportunity to support their families or fleeing from gangs, corruption or extortion.
Over the last three summers, the Trump administration has struggled to curb the migrant surge.
As recently as March, the homeland security secretary at the time, Kristjen Nielsen, met with leaders of the three Central American countries in a similar appeal to halt what she described as a humanitarian crisis. The next day, Mr. Trump undercut her efforts by saying Guatemala, Honduras and El Salvador “do nothing” to stop the migrants from heading north. He also cut millions of dollars in annual aid to the countries.
Ms. Nielsen resigned days later.
In Guatemala this week, Mr. McAleenan offset requests for restoring the money by offering hands-on assistance from Border Patrol agents and homeland security investigators.
In a predawn raid on Wednesday, the investigators joined Guatemalan police to break up a human trafficking ring. Among the 10 arrest warrants served was one for Luis Augusto Torres Rosales, known as “Bimbo,” who the authorities suspect had illegally transported dozens of migrants from El Salvador and Honduras through Guatemala to Mexico. As Mr. Rosales was taken away in handcuffs, his grandmother wept.
Mr. McAleenan, a career law enforcement official, said the human smugglers take advantage of vulnerable Central Americans seeking better lives. With the new deployments of the American agents, he said, “I think we’re going to see a response in Guatemala that’s focused on the safety of children.”
Additionally, dozens of Border Patrol agents are being sent to Guatemala to help the local authorities build checkpoints and make sure incoming migrants from Honduras or El Salvador are carrying legal immigration documents. The American agents will be deployed from their current stations along the United States’ northern and southwestern borders.
“We’re going to try and interdict this flow where it starts,” Mr. McAleenan said this week. “We’re going to try and impact and disrupt the smuggling cycle on the numbers that are heading toward our border.”
With farmers and nongovernment organizations that depended on the American aid, however, he took on the role of a listener and note-taker who promised to take their requests for funding back to Washington.
During a discussion in Nueva Santa Rosa, more than an hour south of Guatemala City, one farmer said that the money had helped him grow more bell peppers. “What I’m interested in is we do not lose that support,” one farmer told Mr. McAleenan in Spanish. “Not only for me but the community who thinks of migrating on a day-to-day basis.”
“I hope you will continue to give this aid,” another worker said. “Many of our relatives are leaving. It is very sad to see your people go.”
Some of the State Department funding had been given to Popoyán, an agribusiness that helps train Guatemalan farmers to use technology to manage their crops.
“Do other farmers benefit from the technology?” Mr. McAleenan asked another farmer.
“That is correct,” the man responded. In a rare moment of levity, Mr. McAleenan asked the farmers who was caring for their crops as they met with him.
“Our wives,” the men said as the group broke into laughter. “Our relatives.”
In a separate meeting, Mr. McAleenan encouraged aid workers to voice their concerns about the funding cuts, according to three people in attendance, so that he could discuss it with Secretary of State Mike Pompeo.
In an interview later, Mr. McAleenan said aid workers had supplied him with necessary data to show others in the Trump administration that the funding had supported programs that were effective.
Without it, “a lot of dreams will be crushed,” said Ivanna Sofía Meneses Müller, a spokeswoman for Popoyán, said in a separate interview afterward.
But Mr. Trump’s threat to punish Mexico for failing to stop the migrant flow from Guatemala overshadowed the last day of Mr. McAleenan’s diplomatic efforts, raising fears that Washington would maintain only a punitive approach to preventing migration.
John Cohen, a former acting under secretary at homeland security during the Obama administration, said programs to curb the migrant flow, whether through diplomatic aid or cracking down on crime in home nations, have proved productive.
But, he said, those efforts “are undercut by those in the White House who obviously have the president’s ear but really don’t have an accurate appreciation and understanding of how you address the issue of illegal immigration.”
“That’s the dichotomy,” said Mr. Cohen, who also worked in homeland security during the Bush administration.
Pascale Wagner, the director in Guatemala for the humanitarian organization Project Concern International, said the funding cuts would have far longer ramifications than a few years’ worth of crops.
“It’s a question of our reputation,” said Ms. Wagner, whose group gives 6,000 families $60 a month, and teaches them about economic resiliency. “We can explain it as much as we want, why the programs are being cut. But that is devastating.”
“To rebuild trust would take years,” she said.