In our weekly look at how the government is using science to safeguard the nation, Center for the Study of Weapons of Mass Destruction CEO Randall Larsen talks with Joan Rohlfing, the President of the Nuclear Threat Initiative. The topic, preventing nuclear terrorism. They have just released a new documentary called "Nuclear Tipping Point", focusing on conversations with four men intimately involved in American diplomacy and national security over the last four decades -- former Secretaries of State George Shultz and Henry Kissinger, former Senator Sam Nunn, and former Defense Secretary William Perry.