Former presidents Barack Obama, George W. Bush, Bill Clinton, George H.W. Bush and Jimmy Carter during the dedication of the George W. Bush Presidential Center at the George W. Bush Presidential Library and Museum on the campus of Southern Methodist University in Dallas, Texas, April 25, 2013.Official White House Photo by Pete Souza

Secretary of State Mike Pompeo at Paya Lebar Air Base, Singapore, as President Donald J. Trump arrives for the summit with North Korean leader Kim Jong Un, June 10, 2018. Secretary Pompeo travels to Singapore, June 10–13, where he will participate in the President’s summit and bilateral events with Singaporean Prime Minister Lee Hsien Loong. State Department photo/ Public Domain