Soldiers patrol the U.S.-Mexico border area near Presidio, Texas, on March 25, 2025. (Rueben Gaeta/U.S. Army)

The Pentagon has spent about $376 million on new border operations for thousands of active-duty service members since President Donald Trump’s return to the White House, Defense Department officials told lawmakers Tuesday.

The new military deployments have surged to the southern border since Jan. 20 when Trump ordered the Defense Department to support efforts by the Department of Homeland Security to seal the border.

The enhanced military mission will likely be measured in “years not months,” Air Force Gen. Gregory Guillot, the commander of U.S. Northern Command, told the House Armed Services Committee.

Guillot testified alongside Adm. Alvin Holsey, who leads U.S. Southern Command, Rafael Leonardo, the acting assistant defense secretary for homeland defense and hemispheric affairs, and Robert Salasses, who leads the Pentagon’s Washington Headquarters Services.

“The initial results of sealing the border have been fantastic, if you look at the stats, but we need to make sure that that’s lasting and goes through all the cycles of illegal migration that we see — seasonal impact is significant on this,” he said. “And then we need to make sure that it is sealed, and it remains sealed. And I think that will take probably a couple of years.”

Guillot reported a 97% drop last month in migrant crossings at the southern border, according to Customs and Border Protection data that showed only 11,709 crossings in February compared with 189,913 in February 2024. It marked the lowest reported migrant crossings in years, down from a previous high of about 302,000 in December 2023.

Air Force Gen. Gregory Guillot, the commander of U.S. Northern Command, testifies on April 1, 2025, during a House hearing about the southern border mission. (Eric Kayne/Stars and Stripes)

Pentagon officials who testified Tuesday did not provide additional details about the money spent on the new operations, including what the operations might cost in the future.

The Pentagon now has about 6,700 active-duty troops deployed to support Homeland Security in their border operations, according to Guillot. The general said he expects the new active-duty deployments to reach about 10,000 troops soon. The National Guard had already deployed some 2,500 forces on the border mission, which dates back years.

Another roughly 1,000 troops have been sent to Naval Station Guantanamo Bay in Cuba to support Homeland Security’s operations to detain some migrants there ahead of their scheduled deportations, according to the Pentagon.

At the border, troops work with Border Patrol agents to identify and monitor migrant movements, provide transportation and vehicle maintenance, data entry services, warehousing and logistical support, officials have said. Active-duty troops are prohibited by law from conducting arrests on U.S. soil and rarely directly interact with migrants.

Guillot said when troops identify migrants crossing the border and Border Patrol agents are not immediately available, they can only continue to monitor the migrants. The general said he has received no orders to expand troops’ authorities to conduct law enforcement operations.

Recent deployments have included helicopter units, which can conduct aerial reconnaissance for Border Patrol agents, and infantry units with Stryker combat vehicles. The mission also includes engineers, logisticians, drone operators and intelligence analysts, defense officials have said. In recent weeks, the Navy has also deployed two destroyers to support border operations.

Guillot told lawmakers that his forces could be more effective if they were authorized to shoot down drones along the border. The general said he would like to give troops operating within 5 miles of the border permission to shoot down small drones flown from Mexico. He said it was the only change that he had requested in their ability to use force. For now, troops close to the border carry rifles or handguns and are only authorized to use force for self-defense or to shoot down drones that are flying over military installations.

Lawmakers — mostly Republicans — said Tuesday that the latest Border Patrol data proves the effectiveness of Trump’s border efforts, including the use of active-duty forces. Rep. Pat Fallon, R-Texas, said the new border efforts have made him “feel safer today than I have in a very long time.”

“We didn’t need new policies,” said Rep. John McGuire, R-Va. “We needed a new president who was serious about protecting the homeland.”

Others said they worried the deployments could eat away at combat readiness with thousands of troops sitting around at the border with little to do. Last year, Army Gen. Daniel Hokanson, then the chief of the National Guard who has since retired, told lawmakers that the border mission provided his force “no military training value.”

Several Democrats on Tuesday told Guillot that they worried the troops along the border would be better off at their home station preparing to fight a war against an adversary such as Russia or China.

Having 6,500 troops at the border, said Rep. Salud Carbajal, D-Calif., “sounds like an excessive number to me.”

Rep. Gabe Vasquez, D-N.M., whose district includes about 180 miles of the southern border, said he was grateful for the impact the operations have had on drug trafficking, but he was concerned the Defense Department was taking an outsized role in the effort.

“It is [Homeland Security’s] job to enforce our domestic immigration laws,” Vasquez said. “And I believe DOD has to remain focused on preparing to fight and win America’s wars. And I’m very concerned the department is wasting some of these precious resources.”

Guillot defended the deployments, saying the operations have proven effective to date in curbing illegal migration and dealing blows to the Mexican cartels, which Trump deemed terrorists earlier this year.

Sealing the border has damaged cartel operations, he said, including an estimated 40% drop in drugs entering the United States via the southern border.

“They’re now trying to find new ways to get their products, whether that’s drugs or people, across the border, because of the seal efforts that have gone on over the last two months,” Guillot said. “That’s also forced them to have more cartel-on-cartel violence as the limited ability to get across the border has forced cartels to incur into other cartels’ territories to try to get across, and so we’re seeing an increase in that violence as well.”