Hours after Trump’s inauguration, his administration canceled appointments allowing migrants to enter the U.S. to request asylum, leaving many of them stranded on the U.S.-Mexico border.

U.S. Customs and Border Protection announced Monday that the CBP One app that worked as recently as that morning would no longer be used to admit migrants. Tens of thousands of appointments were canceled.

Immigration officials are already taking action along the Texas-Mexico border. The American Civil Liberties Union has already filed at least one lawsuit.

President Trump’s executive orders on immigration face legal roadblocks. But he’s still sending U.S. troops to the southern border, and threatening to investigate local officials who stand in the way of arresting and deporting people.