Shielding the South: the historic military deployment on the border with Mexico

From the famed Black Hawk helicopters to destroyers with anti-terrorism experience in the Middle East, the Armed Forces (FFAA) have deployed an unprecedented number of troops to the southern border. Their mission? "Protecting the territorial integrity of the United States." Land, sea and air.

So commanded Donald Trump months ago in his first hours as president, and therefore also as head of the Armed Forces, when, among 25 other executive orders, he signed one "clarifying" the role of the military: border control became a military priority, criminal activities such as illegal immigration and drug trafficking came to be considered "forms of invasion."

The order marked a "shift in national security priorities," according to Maj. Wes Shinego, an Army press officer. The start of a "multifront campaign," including executive action, international cooperation and boots on the ground.

The first deployment took a day and a half. Some 1,500 active troops joined the 2,500 reservists already in the area. A figure that represented an increase over 2024, but not out of step with historical records. According to data from the Center for Strategic and International Studies (CSIS), in 2023 there were also 1,500 active troops and 2,500 National Guardsmen. In 2020, there was 2,500 of each.

At the beginning of March the number of military personnel on the border climbed to about 9,000. A figure that, according to the same data, represents a maximum since the 1990s, when, assures Mark Cancian, CSIS analyst, "the border became an issue."

In addition to pointing out that the previous peak of troops deployed in the South had been marked by George W. Bush, Cancian relativized that data for VOZ: the current troop level is still "relatively modest" compared to others, such as in Korea or Europe. While in the former there are more than 28,000 U.S. uniformed personnel, in the latter there are more than 80,000.

Troops to which were added 10,000 military personnel deployed by Mexico on its side of the border as part of a collaboration agreement.

Helicopters, rotorcraft and destroyers

"Lighter than tanks, yet more robust than light infantry," Major Shinego assures that the Stryker armored vehicle is "ideal for the border's vast terrain." Composed of an armored platform and eight wheels, it can maintain speeds of 60 miles per hour (96 kilometers per hour).

A Stryker brigade combat team was sent to the border in March. At that time UH-60 Black Hawks, "for command and medical evacuation," and CH-47 Chinooks, "for heavy lifting," were also sent.

Originally designed for both transport and assault, the Black Hawks will be limited to the former task, focusing on command and emergency medical missions.

March also saw the announcement of two destroyers: the USS Spruance (DDG 111)and the USS Gravely (DDG 107). Both with the mission to "restore territorial integrity at the US southern border," although the former on the west coast and the latter in the Gulf of America.

Before setting sail for the border waters, the two Arleigh Burke-class guided missile boats were tasked with securing commercial transit threatened by Houthi rebels, a terrorist gang that began firing missiles at commercial vessels in support of Hamas.

Both the USS Spruance and the USS Gravely will carry on board, in addition to their crews, a detachment of the Coast Guard, which has among its prerogatives the interception of illegal immigration. The latter are in charge of detaining illegal immigrants, while the military is limited to support tasks.

Military officials and experts have repeatedly stressed this last point: the camouflaged border guards perform tasks that facilitate the work of the border agencies, but they do not come into direct contact with the immigrants. Above all, they cannot arrest them. Weeks ago, that ceased to be true.

Can the military arrest illegal immigrants?

Troops have been performing support duties for decades that allow Border Patrol agents to focus on their immigration functions. For example, monitoring tasks or moving resources (from food and water to personnel). Or others such as building or repairing physical barriers:

The Department of Defense (DOD), with Pete Hegseth at the helm, has been expanding the Army's powers. He ordered, for example, that troops (hitherto static) begin patrolling the border, on foot or aboard Strykers.

This directive allows them to "cover a larger area," and also "adds an element of unpredictability for those considering illegal entry into the country," assured the Defense Department. "Knowing soldiers are on the move makes it harder to plan movements or cross locations."

The soldiers also received, weeks later, presidential permission to take control of federal land along the border.

Weeks ago, Hegseth again expanded military's duties: they will now be able to detain undocumented immigrants, though only on a delimited strip of the border. Some 109,000-plus acres of land ceded by the Interior Department to the Defense Department for three years.

The area comprises more than 109,651 acres of federal land ceded over three years by the Department of Interior to the Department of Defense. DOD made the area part of the Fort Huachuca military installation. Anyone who enters, therefore, is entering a military base. Soldiers can stop them.

"This is Department of Defense property," Hegseth said during a visit to the area, dubbed New Mexico National Defense Area (NMNDA). "You will be detained. You will be interdicted by U.S. troops and border patrol working together."

Although inside the area they can detain and search illegal immigrants, outside these tasks are still prohibited by law. But even inside the NMNDA they can only hold detainees until they can refer them to CBP.

Analysts tend to agree that the Administration will continue to expand the ADFA's duties depending on the trend of illegal immigration. If it increases, it will increase troops and their duties; if it decreases, it will decrease troops and their duties. Early indicators point to the second scenario: