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

A boy dressed as the Star Wars character Darth Vader attends a Star Wars themed church service, at the Zion Church in Berlin, Sunday, December 20, 2015. About 500 people, some carrying light saber props or wearing Darth Vader masks, attended the service, more than twice as many as usual on a Sunday. (Photo by Markus Schreiber/AP Photo)

Cheering The News of Germany's Surrender New Yorkers Gather around a youth wearing a mask of Adolf Hitler to cheer the news of the Surrender of Germany on May 7. The Crowd is gathered in times Square, New York. May 08, 1945. (Photo by New York Post/Photo Archives, LLC via Getty Images)

U.S. Marine Lt. Ben Reid from 1/2 Charlie Company of Task Force Tarawa waits to be medivaced after being hit with shrapnel and a machine gun round, in the southern Iraqi city of Nasiriyah, on March 23, 2003. The Marines suffered a number of deaths and casualties during gun battles throughout the city. (Photo by Joe Raedle via The Atlantic)

In this November 2, 2017 photo, Mathew Fulkerson and his wife Leigh Ann pose at their Subterra Airbnb located in a former underground missile silo base near Eskridge, Kan. It was designed to house a nuclear warhead six decades ago – but now, this Cold War silo is the perfect spot for a mini break at just $133 a night. (Photo by Thad Allton/The Topeka Capital-Journal via AP Photo)

An inmate covers his head as he passes the time inside Quezon City Jail in Manila, Philippines October 19, 2016. Nearly 2,300 drug users and dealers have been killed in police operations or by suspected vigilantes since Duterte took office on June 30, according to the Philippines police. (Photo by Damir Sagolj/Reuters)

A Russian trenchmortar crew run to take up a new firing position in the Stalingrad area during the Great Patriotic War. (Photo by Keystone/Getty Images). October 1942

Female North Korean soldiers parade to mark the 60th anniversary of the signing of a truce in the 1950-1953 Korean War at Kim Il-sung Square, in Pyongyang. (Photo by Jason Lee/Reuters)