A tribesman loyal to the Houthi movement carries his rifle as he leaves a gathering held to show support for the group, in Yemen's capital Sanaa December 15, 2015. (Photo by Khaled Abdullah/Reuters)

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

Looters scramble in Philipsburg, St. Maarten, Sunday September 10, 1995 for goods in the Ram's department store, which contained mostly food and liquor. No attempts are currently being made by Dutch troops on the island to stop the looting, since few relief supplies have arrived in St. Maarten, which was ravaged on Tuesday by Hurricane Luis. (Photo by John McConnico/AP Photo)

Extraordinary images of the cruise ship by Jonathan Danko Kielkowski from his book Concordia, published by White Press. The German photographer swam out to where the ship – which ran aground off Tuscany in 2012 with the loss of 32 lives – is moored. Francesco Schettino, the ship’s captain, was jailed for 16 years over the accident. (Photo by Jonathan Danko Kielkowski)

Attnedees dressed in Zombie outfits walk down the Gaslamp Quarter outside of the 2015 Comic-Con International in San Diego, California July 8, 2015. (Photo by Sandy Huffaker/Reuters)

These black-and-white photos are taken from the new book “Armoured Warfare in the First World War 1916 – 1918” by Anthony Tucker-Jones and published by Pen & Sword Military. Here: British troops hitch a ride on a Mark IV after the massed tank fleet spearheading attack at Cambrai on November 20, 1917. (Photo by Anthony Tucker-Jones/Mediadrumworld.com)

Monks take pictures with their mobile phones of the mummified body of a monk at Puzhao temple in Quanzhou, Fujian Province, China, January 10, 2016. According to local media, the monk named Fuhou died three years ago at the age of 94 and his remains was placed in a vat and turned into a mummy as a sign of respect. (Photo by Reuters/Stringer)

A boy uses a mobile phone as he sits inside his father's snacks shop along a road in Kolkata, India, February 22, 2016. (Photo by Rupak De Chowdhuri/Reuters)