A Polisario fighter sits on a rock at a forward base on the outskirts of Tifariti, Western Sahara, September 9, 2016. At a rocky outpost in Western Sahara, a new generation of soldiers who have never known war are mobilising as tensions resurface in one of Africa's oldest disputes after a quarter century of uneasy peace. (Photo by Zohra Bensemra/Reuters)

Israelis in costumes spray water on each other during the annual Tel Aviv Water War on Hbima Square in Tel Aviv, Israel,10 July 2015. The annual water fight is on his 11th edition. (Photo by Abir Sultan/EPA)

London Mayor Boris Johnson takes part in a tug of war with members of the armed services to launch the London Poppy Day, outside City Hall, in London, October 27, 2015. London Poppy Day is a street collection event to raise money for serving and retired members of the armed services and their families. (Photo by Stefan Wermuth/Reuters)

Boys dressed in historical uniforms stand before a military parade in Red Square in Moscow November 7, 2014. The parade marked the anniversary of the 1941 parade when Soviet soldiers marched through the Red Square towards the front lines of World War Two. (Photo by Maxim Shemetov/Reuters)

A World War II era P-51 Mustang fighter plane stands in front of a modern 747-8 freighter and a 757 passenger jet at The Boeing Company's centennial celebration in Renton, Washington, U.S. July 15, 2016. (Photo by Alwyn Scott/Reuters)

A hot air balloon in the likeness of Yoda from Star Wars prepares for liftoff at the 21st Philippine International Hot Air Balloon Festival at the former Clark US Air Force base in Pampanga Province, Philippines on February 9, 2017. (Photo by Xinhua News Agency/Rex Features/Shutterstock)

Mae Zelinsky, left, and Betty O'Beda test ammunition on a .30 caliber rifle at a Remington Arms plant on April 30, 1943. Many women took over jobs that were left vacant when men went overseas to fight in World War II. (Photo by AP Photo)

A reveller reacts amid a “flour war” during the “Ash Monday” celebrations, a traditional festivity marking the end of the carnival season and the start of the 40-day Lent period until the Orthodox Easter, in the port town of Galaxidi, Greece, on March 11, 2019. (Photo by Aris Messinis/AFP Photo)