Canada's Prime Minister Justin Trudeau speaks with former President Barack Obama at a restaurant during Obama's visit to address the Montreal Chamber of Commerce, in Montreal, Quebec, Canada June 5, 2017. Prime Minister's Office/Handout via REUTERS
Barack Obama waves after speaking at the Global Food Innovation Summit in Milan, Italy May 9, 2017. REUTERS/Alessandro Garofalo
Barack Obama gestures as he delivers his keynote speech to the Montreal Chamber of Commerce at the Palais de Congres in Montreal, Quebec, Canada June 6, 2017. REUTERS/Dario Ayala
German Chancellor Angela Merkel and Barack Obama attend a discussion at the German Protestant Kirchentag in front of the Brandenburg Gate in Berlin, Germany, May 25, 2017. REUTERS/Axel Schmidt
Barack Obama stands onstage after receiving the 2017 Profile in Courage Award during a ceremony at the John F. Kennedy Library in Boston, Massachusetts, May 7, 2017. REUTERS/Brian Snyder
Caroline Kennedy presents the 2017 Profile in Courage Award to Barack Obama, as former first lady Michelle Obama looks on, during a ceremony at the John F. Kennedy Library in Boston, Massachusetts, May 7, 2017. REUTERS/Brian Snyder
Barack Obama greets supporters after speaking at a community event on the Obama Presidential Centre at the South Shore Cultural Centre in Chicago, Illinois, May 3, 2017. REUTERS/Kamil Krzaczynski
Barack Obama (C) meets with youth leaders Kelsey McClear (L) from Loyola University, Ramuel Figueroa (2nd L) from Roosevelt University, pharmacist Dr. Tiffany Brown (3rd L), Max Freedman (3rd R) from University of Chicago, Harish Patel (2ndL) from...more
Barack Obama speaks during a meeting with youth leaders at the Logan Center for the Arts at the University of Chicago to discuss strategies for community organization and civic engagement in Chicago, Illinois, April 24, 2017. REUTERS/Kamil...more
Barack Obama reacts after addressing staff and guests before boarding Special Air Mission 28000, a Boeing 747 which serves as Air Force One, at Joint Base Andrews, Maryland, January 20, 2017. REUTERS/Brendan McDermid
President Donald Trump (L) greets Barack Obama after being sworn in as the 45th president of the United States on the West front of the U.S. Capitol in Washington, January 20, 2017. REUTERS/Lucy Nicholson
Barack and Michelle Obama board Special Air Mission 28000, a Boeing 747 which serves as Air Force One, at Joint Base Andrews, Maryland, January 20, 2017. REUTERS/Brendan McDermid
Police raid properties as mourners lay flowers following the third militant attack in Britain in less than three months.
Equipment seized over the years, used in cheating attempts by students sitting for the national college entrance exam known as "gaokao", include wireless...
Iraqi forces battle to retake the last enclaves held by Islamic State militants.
Volunteers treat injured protesters affected by rubber bullets and tear gas during demonstrations against President Nicolas Maduro.