The Department of Homeland Security has asked for 20,000 National Guard troops to assist with immigration roundups across the country, and the Pentagon is reviewing the unusual request, a U.S. officia

The Department of Homeland Security is requesting 20,000 National Guard members for help with the Trump administration's crackdown on immigration at the southern border. New York Times Pentagon Correspondent Helene Cooper and Senior Editor at The Atlantic Hanna Rosin join Katy Tur to explain more.