Donna, Texas —

They say they want to legally seek asylum in the United States. Many of the Central Americans walking from Honduras to the US-Mexico border are resting and recharging in Mexico City.

The last time President Trump tweeted about the caravan was before Tuesday’s midterm elections. However, the troops he deployed to the border have not stopped working to prepare for the caravan’s arrival.

On Thursday, the government escorted members of the media on a controlled tour of the military’s temporary base in Donna near the southern tip of Texas.

It’s been a busy week for the U.S. Army in South Texas as military vehicles carrying equipment and supplies pour in to Camp Donna. The military said that the provisional base is a ‘life support area’ located next to the Donna port of entry.

After days of speculation about the military’s role along the border, Northern Command invited the media on a guided, government-organized tour to talk about the army’s day-to-day responsibilities.

“When the soldiers come in, I give them a place to stay,” said base camp mayor Capt. Lauren Blanton. “I give them the food, the lodging and make sure they have medical treatment.”

Camp Donna is a temporary base where there are now more than 600 soldiers including Army engineers, technicians and medics.

So far, 2,800 have been deployed along the Texas border, 1,500 in Arizona, and 1,300 in California – activated by the president in response to the possible arrival of migrants at least 600 miles away.

The military describes their role as simply providing equipment and logistical support to customs and border protection – a go-to phrase for everyone we spoke to at the camp.

“All we’re doing is we’re toughening and expanding on the protections of these port of entries,” said Army 1st Lt. Kevin Barron.

But what does that really mean?

The clearest example we found was 20 miles west, at the Hidalgo port of entry, where soldiers – at the request of Customs and Border Protection (CPB) – have been installing concertina wire all along and around the bridge and the river bank.

“It’s not really meant to keep from crossing, more of just creating a channel of where they can go and not go,” said Army Specialist Zachary James, referring to the concertina wire.

When asked how the military would respond in the event CBP isn’t able to contain a large group of migrants forcefully trying to make it across into the U.S., Lt. Barron said:

“That’s not really our job… to respond to the migrant caravan.”

Lt. Barron explains a law – known as the Posse Comitatus Act – which limits the army’s role and cannot act as immigration agents or domestic police. However, it does provide exceptions to the rule in the case of an ‘invasion’, which is how President Trump has labeled the caravan.

Military leaders stand firm that their response is solely to support CBP.