Campers set structures on fire in preparation of the Army Corp's 2pm deadline to leave the Oceti Sakowin protest camp on February 22, 2017 in Cannon Ball, North Dakota. Activists and protesters have occupied the Standing Rock Sioux reservation for months in opposotion to the completion of the Dakota Access Pipeline. (Photo by Stephen Yang/Getty Images)

Nuns from the United States dance as they wait for the Holy Mass with Pope Francis (not seen) at the Campus Misericordiae in Brzegi, Poland, 31 July 2016. Today Pope Francis will celebrate the holy mass ending the World Youth Day 2016 in Poland. (Photo by Marcin Obara/EPA)

Aviator Frantisek Hadrava moves Vampira, an ultralight plane based on the U.S.-design of light planes called Mini-Max, out of a garage in the village of Zdikov, Czech Republic, August 23, 2016. Frantisek thought driving to work for 14 minutes was too much, so he built an plane to cut the commute by half. (Photo by David W. Cerny/Reuters)

A competitor reacts ahead of Tough Guy Mudathon event in Perton, Britain, 04 February 2018. The original event which started in 1987 raises money for charity and challenges thousands of international competitors with a cross-country run followed by an assault course consisting of 20 obstacles including water, fire and tunnels. (Photo by Nigel Roddis/EPA/EFE)

Local priests celebrate the “Aimara New Year”, an Andean Bolivian traditional festival that marks the winter solstice in El Alto, Bolivia, 21 June 2016. Aimara or Aymara means the Return of the Sun. (Photo by Martin Alipaz/EPA)

Palestinian children warm themselves by a fire on a stormy day at Shati (beach) refugee camp in Gaza City January 18, 2016. (Photo by Mohammed Salem/Reuters)

Horses from the Garrison Savannah, who are involved in celebrations today to mark 50 years of Independence, are washed in the sea first thing in the morning on December 1, 2016 in Bridgetown, Barbados. Prince Harry is visiting the Caribbean marking the 35th Anniversary of Independence in Antigua and Barbuda and the 50th Anniversary of Independence in Barbados and Guyana. (Photo by Chris Jackson/Getty Images)

Urszula Sidoruk, 19, from the paramilitary group SJS Strzelec (Shooters Association), trains her workout at a gym in Siedlce, eastern Poland March 18, 2014. Inspired by the war in Ukraine, growing numbers of Poles are joining volunteer paramilitary groups, where they receive basic army training and prepare to defend their homeland. (Photo by Kacper Pempel/Reuters)