An armed forces members patrol during an operation against drug dealers in Vila Kennedy slum in Rio de Janeiro, March 7, 2018. (Photo by Pilar Olivares/Reuters)

A duck swims in a Osterbekkanal during a the rainy autumn afternoon, central Hamburg, Germany 20 November 2017. (Photo by Srdjan Suki/EPA/EFE)

Sudanese cattle keepers from Dinka tribe Makal Maker (R) and Achiek Butich pose with the guns for their protection at their cattle camp in Mingkaman, Lakes State, South Sudan, on March 2, 2018. (Photo by Stefanie Glinski/AFP Photo)

Pakistani Rangers (black) and Indian Border Security Force personnel (brown) perform perform during the daily beating of the retreat ceremony at the India- Pakistan Wagah Border Post, some 35 kms west of Amritsar on August 14, 2017. Pakistan celebrates its independence on August 14, one day before India' s independence day on August 15. (Photo by Narinder Nanu/AFP Photo)

Women in yukatas, or casual summer kimonos, take their selfie in front of paper lanterns during the annual Mitama Festival at the Yasukuni Shrine, where more than 2.4 million war dead are enshrined, in Tokyo, Japan July 13, 2017. (Photo by Kim Kyung-Hoon/Reuters)

The War in Abkhazia from 1992 to 1993 was fought between Georgian government forces for the most part, and Abkhaz separatist forces, Russian armed forces and North Caucasian militants. Ethnic Georgians who lived in Abkhazia fought largely on the side of Georgian government forces. Ethnic Armenians and Russians within Abkhazia's population largely supported the Abkhazians, and many fought on their side. The separatists received support from thousands of North Caucasus and Cossack militants and from the Russian Federation forces stationed in and near Abkhazia. Here: Abkhazia. Sukhumi, 1993. A house-to-house combat. (Photo by Andrei Solovyov/ITAR-TASS)

A Wiesel combat vehicle of the German Bundeswehr armed forces takes part in a demonstration for visitors prior to military exercises on September 28, 2011 near Munster, Germany. The Bundeswehr has instituted far-reaching changes in recent years, including an end to compulsory military service. (Photo by Sean Gallup/Getty Images)

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