DONNA, Texas — It's been unseasonable cold, and wet, at this site of a new U.S. base camp that's now home to several hundred active-duty U.S. Army soldiers. They’re part of the more than 5,000 troops Donald Trump deployed to the U.S.-Mexico border ahead of the midterms to ward off the so-called caravan of migrants headed north from Central America. It's a huge taxpayer expense — estimated cost: $200 million — but the troops have virtually nothing to do.

Here at Base Camp Donna, 10 miles east of McAllen, Army engineers have built facilities to accommodate a long-term deployment: It now has hot showers, laundry facilities, and a kitchen to produce two hot meals a day. The medical tent is outfitted for handling all manner of injuries, but there's been nothing much besides mosquito bites and scrapes from the concertina wire they're putting up.

Many of the soldiers here have served in Afghanistan and Iraq, except here, there’s no enemy to fight and no immediate action needed. The migrant caravan they're supposed to be responding to is weeks away and headed to Tijuana, 1,500 miles to the West. The only concrete mission the troops have engaged in so far is “hardening” parts of the border with the spiked wire.

When that’s done, said Major Derek Wamsley, a public affairs officer at the base, “we move back here and wait for the next request from Customs and Border Protection.”