Cadmus developed a crisis simulation led by the president of the United States for more than 50 heads of state and government for the fourth and final Nuclear Security Summit. Cadmus, in coordination with interagency and international partners, developed and produced video injects to support a two-module scenario designed to test coordination and cooperation between heads of state and government during a nuclear crisis. Our expert facilitators guided the world leaders through the exercise using printed facts sheets and briefings, the video-injects, and state of the art polling software to encourage dialogue and present real-time decision making with respect to global nuclear and radiological material security.