Members of the Albert Battery perform a gun salute during the Anzac Day dawn service held by the Currumbin RSL on the Gold Coast in Currumbin, Australia, 25 April 2016. The Anzac day marks the landing of the Australian and New Zealand Army Corps (Anzac) troops at Gallipoli in what is today Turkey during WWI. World War One, also called the Great War, according to official statistics cost more than 37 million military and civilian casualties between 1914 and 1918. (Photo by Glenn Hunt/EPA)

Armed Syrian Turkmen villagers are seen near the northern Syrian village of Yamadi, near the Turkish-Syrian border, Syria, November 24, 2015. Turkey shot down a Russian warplane near the Syrian border on Tuesday saying it had repeatedly violated its air space, one of the most serious publicly acknowledged clashes between a NATO member country and Russia for half a century. (Photo by Reuters/Stringer)

A girl carries a rifle as she attends a rally by followers of the Shi'ite Houthi movement commemorating the death of Imam Zaid bin Ali in Sanaa, Yemen October 26, 2016. (Photo by Khaled Abdullah/Reuters)

A Colombian soldier hugs his girlfriend during the graduation ceremony of soldiers in Nilo, Colombia, February 17, 2017. The soldiers will be deployed to occupy territories formerly controlled by FARC rebels. (Photo by Jaime Saldarriaga/Reuters)

Chinese military medics take part in a parade commemorating the 70th anniversary of Japan's surrender during World War II held in front of Tiananmen Gate in Beijing, Thursday, September 3, 2015. (Photo by Ng Han Guan/AP Photo)

Young man making the O.K. sign. (Photo by George Marks/Retrofile/Getty Images). Circa 1950s

A bakery worker rides a bicycle as he carries fresh bread on his head in Cairo, Egypt, February 9, 2016. (Photo by Asmaa Waguih/Reuters)

A paramilitary police officer (right) turns around as hostesses line up for roll call ahead of the Beijing International Automotive Exhibition in Beijing, China, on Monday, April 25, 2016. Tesla Motors Inc. and BYD Co. are among manufacturers showing 147 new-energy vehicles at this year's show. (Photo by Qilai Shen/Bloomberg)