When President Trump dispatched Fort Carson troops to help secure more than 1,000 miles of mostly rugged and remote terrain along the Southern Border this spring, the flow of migrants northward had already fallen off steeply. 

The soldiers’ job was to seal the border completely, a mission they tackled with an array of tools, such as 100 eight-wheeled armored strykers equipped with thermal cameras with six miles of range instead of weapons, traditional foot patrols and drones gathering aerial imagery, said Col. Hugh Jones, commander of Fort Carson’s 2nd Stryker Brigade Combat Team. The number of Carson soldiers varied from approximately 2,000 to 2,400 in a total force of about 10,000 troops deployed at the border.

There are now about 11,500 service members along the border, Northern Command said.

The technology allowed them to detect border crossers and thousands of drones used to scout crossing locations and carry illegal drugs. 

While the necessity of soldiers at the border to augment the Border Patrol is the subject of ongoing political debate, the visible presence of military personnel and equipment is seen by Trump administration officials as a necessary show of force to deter illegal crossings, plug gaps in enforcement and discourage drug smuggling.

During their almost nine-month stay, days would pass when the soldiers would see no one through their interconnected web of surveillance that spanned Arizona, New Mexico and Texas, Jones said. It’s a territory that features open desert, the vast Big Bend National Park and the dense urban landscape of El Paso, a West Texas border city of approximately 800,000 people. In El Paso, the Rio Grande River starts serving as the international border and cuts a meandering green path between the U.S. and Mexico for more than 1,000 miles. 

While talking with a soldier about the work, Jones said the man told him he had noticed a marked decline in migrants coming over the border during his deployment. 

The soldier told him, “I feel like I’m protecting my country and I’ve achieved something,” Jones recalled.

Soldiers and immigration advocates alike described the Southern Border as quiet, with a low number of border crossers. 

A little more than a week ago in Arivaca, Ariz., near the border, it was “completely quiet”, said Mónica Ruiz House, who works with No More Deaths, a humanitarian group. The aid station has seen 20 people at a time in the past, she said. 

“It’s very eerie,” she said.  

In El Paso, many shelters that housed asylum seekers a few years ago have closed or have low populations, and many migrants are leaving or asking to be deported while they are being detained, said Aimée Sanitillán, a policy analyst for Hope Border Institute who lives in El Paso. 

“There is no more hope,” she said, for those seeking asylum.

WORKING ALONGSIDE BORDER PATROL

When Fort Carson soldiers arrived at the border, they worked in a logistical support role alongside the existing Border Patrol structure, with battalion leaders coordinating with patrol leadership in the large sectors set up by Border Patrol, Jones said. The El Paso sector, for example, includes 268 miles of the border. The company or platoon leaders would partner with the border patrol station leaders to coordinate their operations, providing extra eyes and ears. The border patrol stations are similar to police stations, and in some cases, soldiers worked in the same building as agents. 

Soldiers were only allowed to detain immigrants for trespassing on land controlled by the Department of Defense in National Defense Areas implemented by President Donald Trump over the past year along the border in Texas, Arizona and New Mexico.

On Wednesday, a new National Defense Area was announced in California by the Department of the Interior. Previously, soldiers could only assist Customs and Border Patrol but could not enforce immigration laws directly. 

When soldiers detained migrants in the new National Defense Areas, it was for minutes at a time, until border agents could arrive, Jones said. The soldiers would also stop and provide aid — in one instance, landing a helicopter to help a woman having a heat stroke.

The Posse Comitatus Act generally bars the Army from direct participation in civilian law enforcement in the United States, including enforcement of immigration laws. But the NDAs are treated like military installations, where the military’s authority is based on property protection and allows soldiers to charge those found on the property with trespassing.

During some missions, troops and their equipment had to be flown in by helicopter, and the soldiers had to bivouac on the ground. But few needed to camp. Some stayed in barracks at Fort Huachuca and Davis-Monthan Air Force Base in Arizona and Fort Bliss in Texas, while still others overnighted in motels in small towns like Lordsburg and Deming in New Mexico, Jones said.

The widespread surveillance effort from aircraft radar, and sensors that detect the radio waves used to control drones included Customs and Border Patrol equipment such as seismic sensors and trail cameras, he said.

To stay in constant communication with Border Patrol agents, soldiers carried Motorola radios, explained Maj. Kyle Goodroe, who oversees technology and communication for the brigade. Over time, border patrol agents and soldiers also started to share information via smartphones. 

During the deployment, Fort Carson soldiers received new smartphones that allowed them to see their own locations and the locations of their fellows on a map, he said.    

Soldiers maintained about 40 detection and monitoring sites across their area of influence, sometimes with a manned Stryker that provided good points of observation or deterrence, Jones said. They also placed signs to denote the new National Defense Areas.

When possible, soldiers rotated through jobs, spending a week at a detection site, a week patrolling on foot and then a week training, he said. While the training was limited, they practiced skills like firing mortars and marksmanship. 

To help protect soldiers from the heat during 1,300 foot patrols over nine months, the brigade brought along bed sheets they kept in ice chests to cool those at risk of a heat injury, explained Maj. John Tompkins, who manages logistics for the brigade. New boots, combat shirts and pants designed for summer weather arrived for soldiers during the deployment to help manage the heat as well. 

Fort Carson’s 2nd Stryker Brigade returned to Colorado Springs in November, and it has been replaced with an armored brigade from Fort Bliss, an El Paso-based unit that operates M1 Abrams tanks.

Jones expected the brigade that replaced Fort Carson troops would tackle the mission similarly, using joint light tactical vehicles, similar to Humvees, rather than tanks or Strykers. 

So far, the deployments are estimated to cost $1.3 billion, according to a Wednesday report released by Sen. Elizabeth Warren, D-Mass.

BORDER CROSSING DECLINE

Shortly after taking office, President Trump declared an “invasion” and an emergency at the Southern Border and suspended the ability for migrants to seek asylum, a move that was challenged and temporarily blocked more than once in court. In early December, the administration again paused asylum applications. But as a practical matter, applying for asylum has been largely impossible during the current administration, Sanitillán and others said.

Data from Customs and Border Patrol show that the agency’s enforcement actions, such as taking people into custody or turning people back, have fallen from a peak of about 300,000 in late 2023 to about 11,600 in September 2025, according to the agency.

The number of enforcement actions started to fall dramatically during the Biden administration and had reached less than 100,000 in a month before Trump took office. 

Secretary of Defense Pete Hegseth celebrated the decrease in border crossings and policy changes during a November address. 

“Under President Trump, deterrence is back. After decades of securing other people’s borders halfway across the world, we are finally securing our own border in our own hemisphere,” he said. 

For some living along the border, the increased presence of soldiers is concerning because the troops may not have the same training as local law enforcement on interacting with civilians, said Lilian Serrano, director of the Southern Border Communities Coalition, a group focused on quality-of-life issues along the border. 

“It is very scary and worrisome,” she said. 

However, residents have mostly observed soldiers posted near the border wall, protecting it, she said. 

MILITARY ONE PIECE OF TOUGH ENFORCEMENT

For those living along the border, soldiers and their vehicles are just one piece of tough immigration enforcement under the Trump administration that some described as harsh and hard to predict. 

Immigration and Customs Enforcement officers started arresting migrants at court hearings at the beginning of the summer, and that’s when faith in the system started breaking, said Sanitillán, who lives in El Paso. To help those who are risking arrest, volunteers will accompany people to their hearings and stay in contact with the immigrant’s family if they are detained. 

The group also works with local Catholic churches on how they should respond in case of an immigration action inside one of their buildings. 

The enforcement has created some tension in the city, and there are “a good number of people who have completely isolated,” she said. 

Her group works to educate people on their rights and steps they should take, such as carrying copies of documents, like their permanent resident card or work permits, she said. 

Similar work is happening in cities across the country, such as Chicago, that are seeing aggressive immigration enforcement, Ruiz House said, and some of the focus on immigrant advocacy groups has shifted away from the border completely. 

Brad Jones, a professor of political science at the University of California Davis and faculty affiliate with the school’s Global Migration Center, expects the military presence at the border to persist because there is no obvious political reason for Trump to end the national emergency that allows them to work along the border. 

“It’s almost like an accepted fact of life that the military is going to have a presence on the border,” he said. 

But he, like others, hasn’t observed much activity along the border in Arizona, where he spends time, and found it dropped off before Trump took office. 

“It’s as quiet as anyone has ever seen it,” Jones said.