Two robotic legged squad support system (LS3) machines by the Defense Advanced Research Project Agency follow a technician during a demonstration at Joint Base Myer-Henderson Hall, Virginia, on September 10, 2012. (U.S. Marine Corps photo by Sgt. Mallory S. VanderSchans via The Atlantic)

Members of the public continue to pay their respects at the scene of a hit and run following civil disturbances in the Winson Green area on August 12, 2011 in Birmingham, England. Police are continuing investigations after three people – reportedly trying to protect shops from rioting and looting in Dudley Road – were struck by a car and killed during rioting. Police have so far arrested over 1,000 people following rioting which erupted over a four-day period across the UK. (Photo by Jeff J Mitchell/Getty Images)

A man and his dog wade through a flooded road in Vila Velha, Espirito Santo state, Brazil, on December 27, 2013. At least 44 people have died and more than 60,000 have been left homeless following torrential rains over the past few weeks in southeast Brazil. (Photo by Yasuyoshi Chiba/AFP Photo)

A fan of Serbia scuffles with Albania's Mergim Mavraj during their Euro 2016 Group I qualifying soccer match at the FK Partizan stadium in Belgrade October 14, 2014. The Euro 2016 qualifier between Serbia and Albania was abandoned on Tuesday following a brawl between players from both sides. (Photo by Marko Djurica/Reuters)

A Houthi follower with fake blood on his clothes lies on the ground to represent a victim as others perform a war dance during a ceremony marking the first anniversary of the Houthi movement's takeover of Yemen's capital Sanaa September 21, 2015. (Photo by Khaled Abdullah/Reuters)