Free Syrian Army fighters stand near an ambulance on the eastern edge of the northern Syrian town of al-Bab, Syria, February 27, 2017. (Photo by Khalil Ashawi/Reuters)

Two female soldiers have their picture taken by an army colleague at Mangyongdae. (Photo by Gavin John/Mediadrumworld.com)

In this Monday, June 5, 2017, file photo, an Indian woman walks as se searches for recyclable materials at a garbage dumping site on the outskirts of Gauhati, Assam state, India. (Photo by Anupam Nath/AP Photo)

Fires approach a home near Lower Lake, Calif., Friday, July 31, 2015. A series of wildfires were intensified by dry vegetation, triple-digit temperatures and gusting winds. The golden hills of California were being blackened Friday by a series of wildfires egged on by bone-dry vegetation, triple-digit temperatures and gusting winds. (Photo by Jeff Chiu/AP Photo)

A model presents a creation by Paradizia during Colombiamoda fashion event in Medellin, Colombia, July 29, 2015. (Photo by Fredy Builes/Reuters)

German troops in Stalingrad, USSR. September 10, 1942. (Photo by TASS)

Sister Kate and Sister Claire pose on the beach to promote the documentary film “Breaking Habits?” at the Cannes Film Festival on May 09, 2018 in Cannes, France. (Photo by Regis Duvignau/Reuters)

Ammunition airlift into besieged Khe Sanh, Operation Pegasus, April 1968. (Photo by Larry Burrows/AP Photo)