In this episode, NENSC Co-Chair Daniel Poneman sits down with Dr. Siegfried "Sig" Hecker — the fifth director of Los Alamos National Laboratory and one of the world's foremost authorities on plutonium — for a wide-ranging conversation that spans his arc from a European wartime childhood to the helm of America's premier weapons laboratory. Hecker reflects on the pioneering U.S.–Russia lab-to-lab cooperation he later chronicled in Doomed to Cooperate — securing nuclear materials in the closed Soviet weapons cities after the collapse — along with the end of nuclear testing, the birth of science-based stockpile stewardship, and the live debates over resuming testing and recovering the energy value locked in excess plutonium and used fuel. Drawing on seven trips to North Korea and years assessing Iran, he clo ...