Mattis hails troops' border mission as "very good training"
Migrants traveling with a caravan hoping to reach the U.S. border, wait in line to board buses in La Concha, Mexico, Wednesday, Nov. 14, 2018. Buses and trucks are carrying some migrants into the state of Sinaloa along the Gulf of California and further northward into the border state of Sonora. The bulk of the main caravan appeared to be about 1,100 miles from the border, but was moving hundreds of miles per day. (AP Photo/Marco Ugarte)