A Saudi soldier fires a mortar towards Houthi movement position, at the Saudi border with Yemen April 21, 2015. (Photo by Reuters/Stringer)

American soldiers leaping from an armoured personnel carrier during exercises in Korea, 17th March 1954. (Photo by Three Lions)

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)

A soldier walks on the bank of the river in central Pyongyang, North Korea on April 16, 2017. (Photo by Damir Sagolj/Reuters)

A soldier eats ice cream as she visits a zoo in Pyongyang, North Korea, September 12, 2018. (Photo by Danish Siddiqui/Reuters)

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

In this August 17, 2016, photo, from left to right, Chhering Chodom, 60, Tashi Yangzom, 50, Lobsang Chhering, 27, and Dorje Tandup, 58, drink milk tea on the side of the road. For centuries, the sleepy valley nestled in the Indian Himalayas remained a hidden Buddhist enclave forbidden to outsiders. Enduring the harsh year-round conditions of the high mountain desert, the people of Spiti Valley lived by a simple communal code – share the Earth's bounty, be hospitable to neighbors, and eschew greed and temptation at all turns. That's all starting to change, for better or worse. (Photo by Thomas Cytrynowicz/AP Photo)

British prime minister Winston Churchill (1874–1965) stops to pet a cat at Liverpool Street Station, 24th May 1952. (Photo by Keystone/Hulton Archive/Getty Images)