The approximately 1,300 US troops on the Texas southern border are expected to finish their assigned task of reinforcing border crossing points, largely with concertina wire, in the coming days. Once that work is done, it's not clear what additional orders they will be given other than putting up more wire, according to two defense officials. As of Tuesday there are 5,900 US troops assigned to the border mission in Texas, Arizona and California, according to one of the defense officials. Several hundred troops, however, remain at their various headquarters as planners, while others are part of aviation units. While there are approximately 2,800 troops assigned to the mission of helping protect the Texas frontier, only 1,300 are on the border. Border reinforcements at McAllen have largely been completed, the official said. Similar reinforcements at Brownsville were expected to be completed Tuesday.