Park Geun-hye, President of the Republic of Korea, prepares to depart after her arrival to Joint Base Andrews airfield, March 30, 2016. One of more than 20 countries that are scheduled to arrive 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)