On the 2024 campaign trail, Donald Trump pledged to deploy thousands of troops to secure the southern border of the U.S. as part of his strategy to clamp down on illegal immigration.
The president’s characterization of the situation at the U.S.-Mexico border as an “invasion” had already been met with criticism, which grew with the idea of the domestic deployment of the military.
Democrats, human rights groups, and even some groups within the military itself raised their concerns.
Nevertheless, after his inauguration, troops were deployed to the border within a week, with more following along with U-2 spy planes, Stryker combat vehicles, drones, helicopters, and even two Navy destroyers off the west coast and in the waters of the Gulf of Mexico off Texas.
Approximately 8,600 active duty troops are now at the U.S.-Mexico border, up from about 2,500 at the end of the Biden administration.
Border crossings had fallen sharply in the latter part of Joe Biden’s presidency but plunged as Trump took office. Some 8,000 people were arrested after crossing the border illegally this April, the most recent data shows. The corresponding figure for a year earlier in April 2024 was 128,000.
In the vernacular of the Trump administration: “Promises made, promises kept.”
But what exactly are the troops at the border doing, and is their presence the key factor in the reduction of border crossings? Furthermore, how much does this cost, and what is the overall impact on military readiness? Should they be doing something else somewhere else?
To date, this has all cost around $525 million, according to a figure from the Department of Defense reported in The New York Times.
While the deployments continue to grow, so does the military’s authority over territory along the border. The Pentagon has created two narrow strips of land, effectively turning them into parts of nearby U.S. military bases as a buffer zone with Mexico. They are overseen by Army commands at Fort Bliss, near El Paso, Texas, and Fort Huachuca in Arizona
Any migrants entering these areas are considered to be trespassing on military land and can be temporarily detained by U.S. troops until Border Patrol agents arrive. However, this has faced some legal challenges regarding whether migrants are aware they are trespassing in a restricted area, and there is skepticism about whether many such incidents will occur.
Critics also argue Trump is carrying out an end run around the longstanding Posse Comitatus Act, which generally bars the military from domestic law enforcement.
More than anything, the military’s presence seems to provide a deterrent effect to people smugglers and cartels, and the troops won’t be going anywhere anytime soon. The border mission is expected to last for years to address cyclical and seasonal increases in migration, Gen. Gregory Guillot, the head of the military’s Northern Command, told Congress.
On a day-to-day basis, troops support local law enforcement agencies, patrolling on foot, by helicopter, and in combat vehicles in a highly visible surveillance capacity that also underlines their deterrence capabilities.
The Stryker combat vehicles being used are 25 tons, seat 11, and have eight wheels, reaching speeds of 60 mph. They are often positioned on a strategic overlook where smugglers and cartel members can see them, and vice versa, as they have optical sights that can spot individuals or groups up to six miles away.
To answer the question of what they would otherwise be doing if not deployed at the border, the Times notes that a Stryker battalion in Texas was scheduled for training at Fort Irwin in California and would then deploy to South Korea. Those assignments have been postponed.
Other battalions would similarly be training for deployment in Eastern Europe, the Middle East, or other parts of the Indo-Pacific arena.
On Capitol Hill, this has raised questions as to whether this is the best use of the military. Senator Jack Reed of Rhode Island has been particularly vocal in his opposition. As the top Democrat on the Armed Services Committee, he said on May 8: “It is difficult to explain the border missions as anything but a distraction from readiness.”
His examples were a battalion of Marines that was placing miles of barbed wire across the California mountains; Navy aircrews flying the most advanced submarine hunting planes in the world across the desert; and the two Navy destroyers currently looking out for migrants in boats.
While those sound like perhaps egregious misuses of military time and hardware, the Times spoke with some troops and their commanding officers at the border who said that serving in one of the president’s highest priority missions gave them purpose.
They also argued that they are using skills in the real world rather than in training exercises, as the patrols, planning, mission rehearsals, and surveillance flights they undertake are against actual criminal gangs smuggling people and real Mexican drug cartels.
One commander of a Stryker brigade deployed along the border told the Times that military readiness levels, which are measured by Army standards such as equipment maintenance, were up to 94 percent in April, from 78 percent in December in his unit.
Other commanders argue that the on-the-ground experience is driving re-enlistments among younger soldiers who did not serve in combat overseas, like their older counterparts who served in Afghanistan.
“This is their mission for their generation, and they’re embracing it,” Maj. Gen. Scott Naumann, the head of the Army’s 10th Mountain Division, told the Times.
Naumann moved his headquarters staff to Fort Huachuca in February and oversees Joint Task Force-Southern Border, as it is known.
Nevertheless, concerns about the domestic deployment of troops remain, and Pentagon leaders have traditionally shied away from deployment at the border, fearing it could pull the military into domestic politics.
Peter Feaver, a political science professor at Duke University and an expert on civil-military relations, noted that while there are lots of examples of the military being used domestically, however — except for things like disaster relief — they typicaly “come away from those instances saying, ‘Yeah, we don’t want to do that again.’”
“The military prefers to orient itself towards foreign adversaries,” Feaver said. “It prefers to have other branches of the government, to include other security sectors like police, border police, homeland security, who train for and are optimized for domestic missions — have them do it.”
If the military’s border role remains predominantly deterrence and working in support of civilian law enforcement, then concerns over longer-term cost and the impact on military readiness may remain as concerns.
However, if troop numbers climb and mission creep becomes a factor, costs will also mount, and readiness — the physical ability to redeploy troops that would otherwise be on base in the U.S. or stationed at U.S. facilities overseas, ready to act — may change from being a concern to a real-world challenge.
