 The number of illegal immigrants caught crossing the border has dropped more than 40% in the last three weeks. The president has repeatedly credited restrictions on asylum claims, but those who know the border the best point to the Mexican military's increased involvement. So it's not that we added 22,000 new Border Patrol agents, not because we added a new wall. Mexico plays a very important role. Congressman Henry Cuellar says they're taking migrants off the train and sending them back south. The Texas border Democrat says that's the only way to stem the surge of illegal immigration.