Nursultan Nazarbayev, President of the Republic of Kazakhstan, prepares to depart after arriving at Joint Base Andrews flightline, March 30, 2016. He arrived 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 Nesha Humes/RELEASED)