A resident looks at a wildfire in Vina del Mar, Chile, March 12, 2017. Forest fires are a regular feature of Chile's hot, arid summers, but a nearly decade-long drought combined with historically high temperatures have created tinder-like conditions in the nation's central regions. (Photo by Rodrigo Garrido/Reuters)

An Afghan National Army (ANA) soldier assigned to the Mobile Strike Force Kandak fires a RPG-7 rocket-propelled grenade launcher during a live-fire exercise supervised by the Marines with the Mobile Strike Force Advisor Team on Camp Shorabak, Helmand province, Afghanistan, May 20, 2013. The Marines with the Mobile Strike Force Advisor Team instructed and mentored their ANA counterparts on how to properly utilize their weapons systems. (Photo by SSgt Ezekiel R. Kitandwe/RCT 7)

Soviet Army soldiers sit on their tanks in front of the Czechoslovak Radio station building in central Prague during the first day of Soviet-led invasion to then Czechoslovakia on August 21, 1968. (Photo by Libor Hajsky/Reuters)

A muddied family photograph sits on a hallway stairwell in an apartment block on March 17, 2011 in Kensennuma, Japan. Residents were allowed back to their homes today and began the massive cleanup operation caused by a 9.0 magnitude strong earthquake that struck on March 11 off the coast of north-eastern Japan. The quake triggered a tsunami wave of up to 10 metres which engulfed large parts of north-eastern Japan. The death toll has risen past 5000 with at least 8600 people still missing. (Photo by Chris McGrath/Getty Images)

Students celebrate their A-level results at King Edward VI High School for Girls in Birmingham, England on August 18, 2016. The proportion of top grades achieved by A-level students across the UK has fallen for a fifth year in a row, and girls have caught up with boys in attaining A* grades. (Photo by Joe Giddens/PA Wire)

School teachers and staff members take part during an active shooter training at James I. O'Neill High School in Highland Falls, New York, U.S., December 12, 2017. (Photo by Eduardo Munoz/Reuters)

Models struggle against strong wind before the rehearsal of Christian Dior's Haute Couture Spring-Summer 2017 live show to celebrate Dior's new flagship store on the rooftop of Ginza Six mall in Tokyo, Japan, April 19, 2017. (Photo by Toru Hanai/Reuters)

Police detain an alleged thief in Lagos' Tafawa Balewa Square where the official People's Democratic Party (PDP) opposition party is holding a rally on February 12, 2019. Nigerians will cast their ballots on February 16 in presidential and legislative elections. The presidential contest will see incumbent Muhammadu Buhari seek to win a second four-year term against former vice president Atiku Abubakar in what is expected to be a close race. (Photo by Luis Tato/AFP Photo)