A motorcade for Erna Solberg, Norway's Prime Minister, prepares to depart the Joint Base Andrews flightline March 31, 2016. More than 20 countries arrived here for the 2016 Nuclear Security Summit held in Washington, D.C. The summit provides a forum for leaders to reinforce commitments to securing nuclear materials. (U.S. Air Force photo by Senior Airman Joshua R. M. Dewberry/RELEASED)