A cosplayer prepares before the start of the parade during the Metropoli (Media Culture and Entertainment Festival) in Gijon, northern Spain, July 3, 2016. (Photo by Eloy Alonso/Reuters)

South Vietnamese forces escort suspected Viet Cong officer Nguyen Van Lem (also known as Bay Lop) on a Saigon street February 1, 1968, early in the Tet Offensive. Moments later, Lem was executed by Gen. Nguyen Ngoc Loan, chief of the national police. (Photo by Eddie Adams/AP Photo)

In this photo taken on Friday, July 14, 2017, a student at a paramilitary camp for children calls the rank to attention outside Kiev, Ukraine. As the deadly conflict in eastern Ukraine entered its third year, some parents in Ukraine are anxious to make sure their children are ready to fight it, instead of swimming and playing volleyball. (Photo by Efrem Lukatsky/AP Photo)

A reveller covered in tomato pulp takes part in the annual “Tomatina” festival in the eastern town of Bunol, on August 30, 2017. The iconic fiesta – which celebrates its 72nd anniversary and is billed at “the world's biggest food fight” – has become a major draw for foreigners, in particular from Britain, Japan and the United States. (Photo by Jaime Reina/AFP Photo)

In this March 7, 1991 file photo, a U.S. Marine patrol walks across the charred oil landscape near a burning well during perimeter security patrol near Kuwait City. Twenty five years after the first U.S. Marines swept across the border into Kuwait in the 1991 Gulf War, American forces find themselves battling the extremist Islamic State group, born out of al-Qaida, in the splintered territories of Iraq and Syria. The Arab allies that joined the 1991 coalition are fighting their own conflicts both at home and abroad, as Iran vies for greater regional power following a nuclear deal with world powers. (Photo by John Gaps III/AP Photo)

Police investigators inspect the bodies of two men lying on a sidewalk, who police said were killed after a drug “Shabu” (Methamphetamine Chloride) buy-bust operation in Quezon city, Metro Manila Philippines, October 9, 2016. (Photo by Ezra Acayan/Reuters)

Medic James E. Callahan of Pittsfield, Mass., gives mouth-to-mouth resuscitation to a dying soldier in war zone D, about 50 miles northeast of Saigon, June 17, 1967. Thirty-one men of the 1st Infantry Division were reported killed in the guerrilla ambush, with more than 100 wounded. (Photo by Henri Huet/AP Photo)

A portrait of French WWI soldier Edouard Marius Ivaldi is displayed on a tablet, in this illustration picture, alongside his battlefield grave memorial, a wooden cross with a battlefield helmet in Champagne, eastern France, November 3, 2015. (Photo by Charles Platiau/Reuters)