WASHINGTON, DC - AUGUST 03: U.S. President Barack Obama participates in a Young African Leaders Initiative (YALI) town hall 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 Chris Kleponis-Pool/Getty Images)

Attendees wait to hear US President Barack Obama speak 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 wait to hear US President Barack Obama speak 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: 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)

Attendees wait to hear US President Barack Obama speak 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: 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 catches his foot on a sign and stumbles as he 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)