Women pose for a picture at Havana city, Cuba, March 17, 2016. Obama arrives in Havana on Sunday for a historic visit that seals a rapprochement he and Cuban President Raul Castro agreed in December 2014 after 18 months of secret negotiations. (Photo by Ivan Alvarado/Reuters)

Young monks play inside the Punakha Dzong, Bhutan, April 17, 2016. (Photo by Cathal McNaughton/Reuters)

Young girls carry containers filled with drinking water beside the railway station in Agartala, India, April 20, 2016. (Photo by Jayanta Dey/Reuters)

A girl types on a computer as she demonstrates the interior of the new Volvo S90 during the Auto China 2016 auto show in Beijing April 25, 2016. (Photo by Damir Sagolj/Reuters)

People cross the street in central Pyongyang, North Korea May 4, 2016. (Photo by Damir Sagolj/Reuters)

A woman and a girl dressed in historical Red Army uniform, wait before watching the Victory Day parade, marking the 71st anniversary of the victory over Nazi Germany in World War Two, at Red Square in Moscow, Russia, May 9, 2016. (Photo by Grigory Dukor/Reuters)

A model poses beside a Renault DeZir concept car during the media day of the Shanghai International Automobile Industry Exhibition at Shanghai New International Expo Center on April 20, 2011 in Shanghai, China. The 14th Shanghai International Automobile Industry Exhibition (Auto Shanghai 2011) will be held from April 21 to 28 with the theme of “Innovation For Tomorrow”. About 2,000 carmakers and parts providers from 20 countries are due to showcase 1,100 car models, 75 of which makes their world premieres in the auto show. (Photo by Feng Li/Getty Images)

A Russian trenchmortar crew run to take up a new firing position in the Stalingrad area during the Great Patriotic War. (Photo by Keystone/Getty Images). October 1942