In this June 22, 2016, file photo, Border Patrol agent Eduardo Olmos walks near the secondary fence separating Tijuana, Mexico, background, and San Diego in San Diego. In his threat Tuesday, April 3, 2018, to use the military on the U.S.-Mexico border until his promised wall is built, President Donald Trump again heaped blame on his predecessor, Barack Obama, and congressional Democrats for creating a dangerous and dysfunctional border. (AP Photo/Gregory Bull, File)