US President Barack Obama speaks at the Presidential Summit of the Mandela Washington Fellowship for Young African Leaders at the Omni Shoreham Hotel August 3, 2016 in Washington, DC. / AFP PHOTO / Brendan SmialowskiBRENDAN SMIALOWSKI/AFP/Getty Images

US President Barack Obama speaks at the Presidential Summit of the Mandela Washington Fellowship for Young African Leaders at the Omni Shoreham Hotel August 3, 2016 in Washington, DC. / AFP PHOTO / Brendan SmialowskiBRENDAN SMIALOWSKI/AFP/Getty Images

WASHINGTON, DC - AUGUST 03: Mandela Washington Fellows welcome U.S. President Barack Obama and sing 'Happy Birthday' to him as he arrives at the Presidential Summit of the Mandela Washington Fellowship for Young African Leaders at the Omni Shoreham Hotel August 3, 2016 in Washington, DC. As part of Obama's Young African Leaders Initiative, the summit brought together 1000 leaders, ages 25-35, from across Africa to the U.S. for 6 weeks of leadership training and mentoring at twenty universities and colleges to 'spur growth and prosperity, strengthen democratic governance, and enhance peace and security across Africa.' (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - AUGUST 03: Emmanuel Odama of Uganda (R) welcomes U.S. President Barack Obama to the stage during the Presidential Summit of the Mandela Washington Fellowship for Young African Leaders at the Omni Shoreham Hotel August 3, 2016 in Washington, DC. As part of Obama's Young African Leaders Initiative, the summit brought together 500 leaders, ages 25-35, from across Africa to the U.S. for 6 weeks of leadership training and mentoring at twenty universities and colleges to 'spur growth and prosperity, strengthen democratic governance, and enhance peace and security across Africa.' (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - AUGUST 03: U.S. President Barack Obama addresses the Presidential Summit of the Mandela Washington Fellowship for Young African Leaders at the Omni Shoreham Hotel August 3, 2016 in Washington, DC. As part of Obama's Young African Leaders Initiative, the summit brought together 1000 leaders, ages 25-35, from across Africa to the U.S. for 6 weeks of leadership training and mentoring at twenty universities and colleges to 'spur growth and prosperity, strengthen democratic governance, and enhance peace and security across Africa.' (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - AUGUST 03: Emmanuel Odama of Uganda (R) introduces U.S. President Barack Obama during the Presidential Summit of the Mandela Washington Fellowship for Young African Leaders at the Omni Shoreham Hotel August 3, 2016 in Washington, DC. As part of Obama's Young African Leaders Initiative, the summit brought together 500 leaders, ages 25-35, from across Africa to the U.S. for 6 weeks of leadership training and mentoring at twenty universities and colleges to 'spur growth and prosperity, strengthen democratic governance, and enhance peace and security across Africa.' (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - AUGUST 03: A woman waves a Ugandan flag as U.S. President Barack Obama addresses the Presidential Summit of the Mandela Washington Fellowship for Young African Leaders at the Omni Shoreham Hotel August 3, 2016 in Washington, DC. As part of Obama's Young African Leaders Initiative, the summit brought together 1000 leaders, ages 25-35, from across Africa to the U.S. for 6 weeks of leadership training and mentoring at twenty universities and colleges to 'spur growth and prosperity, strengthen democratic governance, and enhance peace and security across Africa.' (Photo by Chip Somodevilla/Getty Images)

WASHINGTON, DC - AUGUST 03: Emmanuel Odama of Uganda (R) welcomes U.S. President Barack Obama to the stage during the Presidential Summit of the Mandela Washington Fellowship for Young African Leaders at the Omni Shoreham Hotel August 3, 2016 in Washington, DC. As part of Obama's Young African Leaders Initiative, the summit brought together 500 leaders, ages 25-35, from across Africa to the U.S. for 6 weeks of leadership training and mentoring at twenty universities and colleges to 'spur growth and prosperity, strengthen democratic governance, and enhance peace and security across Africa.' (Photo by Chip Somodevilla/Getty Images)