Bob Rosner and Sharon Squassoni of the Science and Security Board at the Bulletin of the Atomic Scientists join Press the Button to discuss why the Doomsday Clock is still at 100 seconds to midnight, and what must happen before the time is moved backwards. Early Warning features Ploughshares Fund's deputy director of policy Mary Kaszynski on the appointment of Rob Malley as special US envoy for Iran, and the complexities behind US and Iran efforts to re-enter the Iran nuclear agreement.