Soldiers from 12 Mechanized Brigade perform a simulated casualty evacuation at the Ministry of Defence training area at Copehill Down on Salisbury Plain on March 9, 2012 in Wiltshire, England. The Defence Secretary Philip Hammond visited the military facility to meet soldiers from the Brigade who are shortly to deploy to Afghanistan for Operation Herrick 16, and troops from the 3rd Battalion, the Yorkshire regiment which lost five of the six men who died this week in the deadliest single attack in Afghanistan since 2001. (Photo by Matt Cardy/Getty Images)

Smoke billows from Jinnah International Airport in Karachi, Pakistan, June 9, 2014. (Photo by Athar Hussain/Reuters)

Three secondary schoolboys smoking an illicit cigarette in Hyde Park, London. (Photo by Evening Standard/Getty Images). May 1972

A girl broadcasts at live streaming talent agency Three Minute TV in Beijing, China on April 12, 2017. Three Minute TV also arranges cosmetic surgery at partner hospitals for its anchors, arranges small bank loans for the surgery, photographs and markets the anchors and helps them find acting opportunities Deng said. (Photo by Damir Sagolj/Reuters)

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)

A 20 metre high spiral staircase in a tower used as an emergency exit, is seen inside a Federal Reserve bank (Bundesbank) bunker, prior to the bunker's official opening to the public in Cochem, Germany, March 18, 2016. West Germany's Central Bank (Deutsche Bundesbank) stored some 20 billion German marks of emergency notes in two underground bunkers, one in Frankfurt the other in Cochem, between 1964-1988 during the cold war. (Photo by Kai Pfaffenbach/Reuters)

A performer presents a creation from the Haute Coiffure Fall-Winter 2014/15 collection by French designer Charlie Le Mindu during the Paris Fashion Week, in Paris, France, July 7, 2014. The presentation of the Haute Couture collections runs from 06 to 10 July. (Photo by Etienne Laurent/EPA)

Buyan, a male Siberian brown bear, is given a shower by a zoo employee in his enclosure at the Royev Ruchey zoo in Russia's Siberian city of Krasnoyarsk June 24, 2014. The Siberian city has been experiencing temperatures of around 30 degrees Celsius over the last week. (Photo by Ilya Naymushin/Reuters)