President Trump made building a border wall between the U.S. and Mexico a cornerstone of his 2016 presidential campaign. Since taking office, he has called for a travel ban on people from Muslim countries. He has limited the rights of asylum seekers and presided over a family separation crisis at the southern border. New York Times journalists Julie Hirschfeld Davis and Michael Shear discuss the decisions and the ideologies shaping US immigration policy with World Affairs co-host Markos Kounalakis.