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)

Shell, which is the replica of the biggest detonated Soviet nuclear bomb AN-602 (Tsar-Bomb), is on display in Moscow, Russia, August 31, 2015. The shell is part of an exhibition organized by the state nuclear corporation Rosatom. (Photo by Maxim Zmeyev/Reuters)

A woman sits on a terrace at Tiki hostel in Cantagalo favela, in Rio de Janeiro, Brazil, April 16, 2016. Hostels in a few of Rio's more than 1,000 slums serve not only as a cheap housing alternative for the more adventurous among the estimated 500,000 foreign tourists expected to arrive for the Olympics in August. The establishments also open up the rich culture of the city's shantytowns for travellers, giving them a glimpse into once “no-go” areas where about one-fifth of Rio's population lives. (Photo by Pilar Olivares/Reuters)

A gibbon drinks from a soft drink bottle, given by a tourist, at a zoo in Kunming, Yunnan province, June 18, 2015. (Photo by Wong Campion/Reuters)

In this July 17, 2015 photo, Michael Chilton squeezes into a corner of his car to make a quick repair to some body panels after he ran into a wall during dirt track racing in the late model division at the Ponderosa Speedway in Junction City, Ky. He banged up the car in the qualifying round and had a few minutes to fix it before the final race. (Photo by David Stephenson/AP Photo)

Iranian Kurdish female members of the Freedom Party of Kurdistan (PAK) hold a position on November 6, 2016 in an area near the town of Bashiqa, some 25 kilometres north east of Mosul, during an operation against Islamic State (IS) group jihadists to retake the main hub city. (Photo by Safin Hamed/AFP Photo)

Smoke and flames rise over a warehouse storing ammunition for multiple rocket launcher systems at a military base in the town of Kalynivka in Vinnytsia region, Ukraine September 27, 2017. Ukrainian officials say they have evacuated more than 30,000 people after a fire and ammunition explosions, at the military base on Tuesday. (Photo by Gleb Garanich/Reuters)

A duck swims in a Osterbekkanal during a the rainy autumn afternoon, central Hamburg, Germany 20 November 2017. (Photo by Srdjan Suki/EPA/EFE)