U.S. Army soldiers arrive at Base Camp Donna, one of multiple military bases being set up along the U.S.-Mexico border, in Donn, Texas, on Nov. 8, 2018. With little electricity, no combat pay and holidays away from home, the 5,600 American troops on the southwest border are on a mission ordered by a politically determined commander in chief and a Pentagon unable to convince him of its perils. (Tamir Kalifa/The New York Times)