A National Army of Colombia soldier, who was wounded by a mine, swims at a pool in Bello, municipality of Antioquia, March 25, 2015. (Photo by Fredy Builes/Reuters)

An American soldier walks ahead of an MKIV (Mark IV) British-made tank, circa 1918. (Photo by Hulton Archive/Getty Images)

Two female soldiers have their picture taken by an army colleague at Mangyongdae. (Photo by Gavin John/Mediadrumworld.com)

South Korean bee farmer Ahn Sang-Kyu protests Japan's claim of sovereignty over disputed islets May 2, 2006 in Seoul, South Korea. Ahn, a local bee farmer, released over 140,000 bees and attracted them to his body to protest Japan's sovereignty claims over a tiny group of islands located off the east coast of South Korea, called the Dokdo islets by the Koreans and Takeshima by the Japanese. The volcanic islets located about 90 kilometres east of South Korea's Ullung Island, have been a source of diplomatic friction between South Korea and Japan for years. (Photo by Chung Sung-Jun/Getty Images)

A South Korean model poses with Peugeot 5008GT during a press preview of the Seoul Motor Show in Goyang, northwest of Seoul, on March 30, 2017. South Korea's largest international auto show will open on March 31, with a total of 27 brands showing their latest cars and concepts. (Photo by Jung Yeon-Je/AFP Photo)

South Korean students pose for a selfie following a traditional coming-of-age ceremony at Namsan hanok village in Seoul on May 15, 2017. The Coming of Age Day is the day to celebrate and encourage the youth who have reached the age of 20, which is considered the beginning of adulthood. (Photo by Ed Jones/AFP Photo)

Russian soldiers write home while serving on the Eastern Front during World War I, circa 1915. (Photo by Hulton Archive/Getty Images)

Israeli soldiers get ready to launch the Skylark drone during a drill on January 16, 2012 near Bat Shlomo, Israel. (Photo by Uriel Sinai/Getty Images)