The Bulletin of the Atomic Scientists yesterday adjusted its Doomsday Clock to two minutes before midnight. The clock was last this close to midnight in 1953.

Created in 1947 to alert us about the potential catastrophe of nuclear weapons, the Bulletin commemorated its 70th anniversary in October 2017, announcing that humanity was at its most dangerous moment since the height of the Cold War. Issues like the Trump administration’s saber-rattling with North Korea and threats to pull the U.S. out of the Iran Nuclear agreement motivated the Bulletin to adjust the clock forward to two and-a-half minutes to midnight.

We’ll talk about events that led to yesterday’s Doomsday Clock adjustment with Rachel Bronson, executive director and publisher of the Bulletin of the Atomic Scientists.