The unusual use of front-line troops on border comes after Trump ordered the military to give priority to border security.

U.S. officials say the Pentagon will begin deploying as many as 1,500 active duty troops to help secure the southern border in the coming days.

President Donald Trump ordered defense officials to come up with a plan in the next 10 days to seal off the U.S. border with Mexico, including the possible deployment of more troops, drones, barriers and building more wall.