A Yemeni soldier, pictured through a vehicle's windscreen, which was damaged by a bullet, gestures out of the window, in Marib, Yemen October 15, 2015. Marib is a city that is heavily armed even by the standards of Yemen, where the ready availability of weapons helped start civil war and is now preventing anyone coming out on top. Yemenis often say there are three guns for every person, a boast that has become an urgent concern in a country where the United Nations says the humanitarian situation is "critical". (Photo by Angus McDowall/Reuters)

Undated UK Ministry of Defence handout photo of an RAF Tornado GR4 which has been painted in Gulf War “desert pink” paint scheme to honour the aircraft type's almost continuous operational service since the Royal Air Force helped liberate Kuwait from Saddam Hussein's forces, taken by SAC Rose Buchanan, which has been shortlisted for the general public to pick their favourite RAF Image of the Year. (Photo by SAC Rose Buchanan/MoD Crown Copyright/PA Wire)

In this photo taken Sunday, March 12, 2017, a girl Abuk walks home with her brothers and friends after collecting clean water from a water point four kilometers away from her home, in Aweil, in South Sudan. As World Water Day approaches on March 22, more than 5 million people in South Sudan, do not have access to safe, clean water, compounding the problems of famine and civil war, according to the UNICEF. (Photo by Mackenzie Knowles-Coursin/UNICEF via AP Photo)

South Korean police officers show their martial arts' skills during the official launch ceremony of the 2012 Seoul Nuclear Security Summit on February 15, 2012 in Seoul, South Korea. The Korean National Police Agency launched a security squad, exclusively established for the successful hosting of the 2012 Seoul Nuclear Security Summit. The 2012 Seoul Nuclear Security Summit will be held in Seoul from March 26-27, 2012. (Photo by Chung Sung-Jun/Getty Images)

People walk past the 23-foot “Unitled (LAMP/BEAR)” outdoor sculpture of a teddy bear by artist Urs Fischer April 8, 2011 in New York City. The 35,000 pound sculpture of a yellow teddy bear with a working lamp will be on display for five months in front of the Seagram Building in Manhattan. The sculpture is expected to sell for more than $10 million at Christie’s Post-War & Contemporary Evening Sale on May 11. (Photo by Mario Tama/Getty Images)

The sun catches on the panels of a 1928 Rolls Royce Phantom at Northington Grange, the summer home of the Grange Park Opera, on April 16, 2011 near Winchester, England. The English Heritage Grade 1 listed Greek Revival style property was the setting for the inter-war Rolls Royce20-Ghost Club members which was founded in 1949 by a group of owners of vintage Rolls Royce cars. (Photo by Matt Cardy/Getty Images)

Visitors look at a giant puppet of a grandmother sleeping on a bed inside St George's Hall in Liverpool, northern England July 23, 2014. The grandmother is one of two giant models made for a World War I commemorative event. (Photo by Nigel Roddis/Reuters)