WASHINGTON, DC - AUGUST 03: U.S. President Barack Obama shakes hands with enthusiastic participants 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: U.S. President Barack Obama urges calm while he shakes hands with participants 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: 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: 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: U.S. President Barack Obama urges calm while he shakes hands with participants 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)

U.S. President Barack Obama speaks at a Young African Leaders Initiative town hall in Washington, U.S., August 3, 2016. REUTERS/Yuri Gripas

US President Barack Obama's suit jacket is seen as he 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

Attendees raise their hands to ask US President Barack Obama a question 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