At Base Camp Donna, US Army troops spend Veterans Day preparing for migrants President Trump ordered the troops deployed to support border patrol.

BASE CAMP DONNA, TEXAS -- On an unusually frigid morning, Army Warrant Officer Silvestre Arroyo was supervising his team on Veterans Day weekend as they prepared a hot breakfast of sausage and grits.

His breakfast customers are the estimated 1,000 troops now stationed at this rural outpost in southern Texas and across the Rio Grande river valley.

Their deployment is an unusual one – inside the United States, ordered by President Donald Trump days before a national election to confront a slow-moving migrant caravan he calls “invaders” and a threat to national security.

“Creature comforts go a long way out here,” said Arroyo, a father of three young children.

Some 5,600 active duty troops have been deployed to the U.S.-Mexico border with the expectation that they could stay through mid-December, missing Thanksgiving with their families. Democrats have called the deployment a political farce orchestrated by Trump in a bid to galvanize his base; Republicans have pushed back, insisting that the border has long needed additional security.

Camp Donna, about an hour inland from South Padre Island, is the primary Army base camp in south Texas that supports troops spread across the Rio Grande river valley. Many soldiers are in tent camps, but the military has gotten creative, too, when it comes to housing.

One unit just down the road from Camp Donna is staying in an empty retail store in Weslaco, Texas that can sleep 200 troops.

Named for the small border town nearby, Base Camp Donna sits on federal land and spans multiple football fields in size.

Nothing existed on this land before the military showed up. Now, there are temporary shelters, massive power generators, hot meals, medical services, even a mobile laundry unit.

Temperatures in south Texas in November can fluctuate wildly – from the high 40 degrees to low 90s in a single week. Some of the tents are heated, others are not.

The primary reason for the deployment is to help the U.S. Customs and Border Protection, or CBP, prepare for a caravan of migrants making their way north through Mexico. These migrants say they are fleeing crushing poverty and war in Central America and want to claim asylum inside the United States.

Trump has responded not only with the military deployment but a new policy: Anyone wishing to seek asylum must do so at a designated port of entry. If caught crossing the border illegally, asylum will not be an option.

Twenty miles west of Camp Donna is the Hidalgo International Bridge, which connects the tiny border town of Hidalgo, Texas to Mexico. It’s the only port of entry for miles where travelers can cross on foot.

From the barbed wire-covered pedestrian walkway, the view of the deep river valley is obscured by reinforced fences. Some of this barbed wire is new, placed there by the Army at the CBP’s direction.

If the migrant caravan makes its way to the Hidalgo bridge, what they will likely see is a line. The border crossing there is already active with men, women, and children crossing back and forth daily, many with passes allowing them to cross the border with relative ease.

For those who don’t have the right paperwork and want to claim asylum – which often can include families and children who cross the border alone – they are funneled into small rooms that look somewhat like doctors’ offices.

It’s the same place that CBP officials will deal with accused drug traffickers and other criminals. From there, border officials will begin interviews to review the person’s claims, kicking off a process that could extend years before being resolved by an immigration court.

Port officials say the current flow of travelers is enough to put their facilities at maximum capacity.

Some holding cells have been converted into temporary bathrooms. Down the hall, a small storage closet keeps snacks and supplies. Folded blankets are stacked high next to shelves filled with clothing, blankets and diapers.

CBP officials try to avoid having people stay overnight here, but that doesn’t always happen. They do not have a plan to process a massive influx of migrants at the port itself.

The Army troops will be there only to provide support, with legal limitations on military force being used within U.S. borders.

For Arroyo, the food technician, the deployment feels like a “field training exercise,” and he says his kids will be excited when he returns home. He’s not sure when that might be, and he knows missing the Thanksgiving holiday with his family is a real possibility.

Arroyo’s father is from Veracruz, Mexico; his mother is from Texas.

When asked by a reporter what his family in Mexico thought of troops like him coming to the border, Arroyo’s eyes shifted to the military’s public relations officer leading a media tour.

“They know that I’m here to perform a mission,” he said after a pause. “That’s kind of the end of it.”

ABC News' Elizabeth Mclaughlin and Luis Martinez contributed reporting.