An undated archive picture shows a dog pulling a Belgian machine gun at an unknown location in northern France. A Viscount in the Armoured Cavalry Branch of the French Army left behind a collection of hundreds of glass plates taken during World War One (WWI) that have never before been published. The images, by an unknown photographer, show the daily life of soldiers in the trenches, destruction of towns and military leaders. The year 2014 marks the 100th anniversary of the start of WWI. (Photo by Collection Odette Carrez/Reuters)

An opposition supporter gestures with a knife during clashes with police in Kibera slum in Nairobi, Kenya on October 26, 2017. Kenyans trickled into polling stations today for a repeat election that has polarised the nation, amid sporadic clashes as supporters of opposition leader ignored his call to stay away and tried to block voting. (Photo by Goran Tomasevic/Reuters)

A woman walk by South Korean police during a anti-terror exercise on March 9, 2012 in Seoul, South Korea. The drill is part of South Korea's preparation for the upcoming 2012 Seoul Nuclear Security Summit, scheduled for March 26 and 27. Some 50 world leaders, including U.S. President Barack Obama, are expected to attend the summit to discuss how to make the world safe without nuclear weapons. (Photo by Chung Sung-Jun/Getty Images)

An RAF Eurofighter EF-2000 Typhoon takes off on March 22, 2011 at the Gioia Del Colle airbase in Italy. After last week's UN resolution which voted for a non-fly zone to be enforced over Libya, sorties have continued to be flown by forces representing the UN coalition from Italian military bases. More than 110 missiles have been fired on pro-Gaddafi strongholds in attempt to knock out the Libyan leaders defences.

A woman poses with a cut-out of Vladimir Putin in the “President Cafe” in Krasnoyarsk, Siberia, Russia, April 7, 2016. Dozens of photos of Vladimir Putin, from childhood to Russian President, hang on the walls of President Cafe in a working-class area of Krasnoyarsk, a city in eastern Siberia. A life-size cut-out of Putin stands by the bar. Images of U.S. President Barack Obama, as well as leaders of Germany and Britain, greet customers in the toilets. (Photo by Ilya Naymushin/Reuters)

An activist takes a selfie during a protest ahead of the 2015 Paris Climate Conference, in Paris, Sunday, November 29, 2015. More than 140 world leaders are gathering around Paris for high-stakes climate talks that start Monday, and activists are holding marches and protests around the world to urge them to reach a strong agreement to slow global warming. (Photo by Christophe Ena/AP Photo)

A girl is seen in a bakery in the old walled town of Harar in eastern Ethiopia, May 19, 2015. Daily life of people in Ethiopia, where elections are held this weekend, is portrayed in the east African nation's churches and mosques, coffee shops and markets, both in the capital Addis Ababa and the walled town of Harar in the east. Ethiopia, home to nearly 100 million people, holds the first poll on Sunday since long-serving leader Meles Zenawi died in 2012. (Photo by Siegfried Modola/Reuters)

Nguyen Thi Vui paddles her boat in the flooded streets of Hoi An, Vietnam, Monday, November 6, 2017. A powerful typhoon that rocked Vietnam has killed dozens of people and caused extensive damage to the country's south-central region ahead of the APEC summit that will draw leaders from around the world, the government said Monday. (Photo by Hau Dinh/AP Photo)