Former Bush defense official on how Trump should handle Iran

Tensions between the U.S. and Iran are inflamed, with the U.S. sending more troops to the Mideast amid what it calls provocation by Iran. Now, a new disruption: Acting Secretary of Defense Patrick Shanahan is stepping down amid reports of domestic violence in his past. Former Pentagon comptroller Dov Zakheim of the Center for Strategic and International Studies joins Judy Woodruff to discuss.