A U.S. official with direct knowledge says a military operation to strike Iran was set to begin last night when the White House called it off. The official spoke on the condition of anonymity because of the sensitivity of the information. The U.S. military targets were a limited set of Iranian radars and missile batteries. No U.S. weapons had been launched when the decision was made to call it off. So, we ask: "How Should the U.S. Respond to the Downing of its Drone?" CNN's Max Foster talks to Liam Halligan, Bonnie Greer and Zoe Williams.