A demonstrator is detained during May Day rallies in Santiago May 1, 2013. (Photo by Ivan Alvarado/Reuters)

A visitor holds an Israeli-made rifle during the 8th International Land and Naval Defense system exhibition, in New Delhi, India, on February 6, 2014. (Photo by Anindito Mukherjee/Reuters)

“Aurora Hunters”. Photographers taking part in a photography tour on the Lofoten Islands in Norway, pull over on the side of the road to take a photo of their first ever Aurora Borealis after spotting it from their tour bus. Photo location: Rystad, Lofoten Islands, Norway. (Photo and caption by Mark Gee/National Geographic Photo Contest)

Walkers cross the river Waalbrug during the first day of the 98th annual four-days walking event, the “Vierdaagse” in Nijmegen, Netherlands, July 15, 2014. The “Nijmeegse Vierdaagse” is an annual public four-day field march which is held since 1909 in the third week of July. (Photo by Erik van 't Wout/EPA)

Soldiers of China's People's Liberation Army march with their weapons during a training session for a military parade to mark the 70th anniversary of the end of World War Two, at a military base in Beijing, China, August 22, 2015. Troops from at least 10 countries including Russia and Kazakhstan will join an unprecedented military parade in Beijing next month to commemorate China's victory over Japan during World War Two, Chinese officials said. The parade on September 3 will involve about 12,000 Chinese troops and 200 aircraft, Qi Rui, deputy director of the government office organizing the parade, told reporters in Beijing on Friday. (Photo by Damir Sagolj/Reuters)

Armed forces veteran Frank Simpson at the Portico library being camouflaged by body artist Carolyn Roper in Manchester, UK on May 16, 2016 as part of the #CountThemIn campaign launched on Monday by the Royal British Legion. (Photo by Jon Super/Royal British Legion/PA Wire)

Bangladeshi Muslim devotees arrive in an over-crowded train to attend the final day of an Islamic congregations' first phase in Tongi, 20 kilometers (13 miles) north of Dhaka, Bangladesh, Sunday, January 10, 2016. The second phase of the annual event, one of the world's largest congregations of Muslims is scheduled to begin Friday. (Photo by A.M. Ahad/AP Photo)

Devotees ride on the roof of a train as they return to the city after attending the final prayers on the first phase of Bishwa Ijtema in Dhaka January 11, 2015. Hundreds of thousands of pilgrims congregated in the Bangladeshi capital Dhaka as the first phase of this year's Bishwa Ijtema, one of the biggest Islamic gatherings in the world after the Haj in Saudi Arabia, came to an end. (Photo by Reuters/Stringer)