In this Thursday, April 11, 2013 photo, North Korean female soldiers stand watch on the river bank of the North Korean town of Sinuiju, opposite to the Chinese border city of Dandong. (Photo by AP Photo)

U.S. Marine soldiers from 31st Marine Expeditionary Unit, Battalion landing team deployed from Okinawa, Japan, participate in the U.S. and South Korean Marines joint landing operation at Pohang seashore on March 29, 2012 in Pohang, South Korea. Though South Korean has remained technically at war with North Korea since the end of the Korean War in 1953, the tension of Korean Peninsula has again raised as Pyongyang's new leader Kim Jong-Eun administration announced to launch a “Satellite” between April 12 to 16. (Photo by Chung Sung-Jun/Getty Images)

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)

In a photo taken on September 11, 2019, North Korean students pose for photos in Chonji lake, or “Heaven lake”, as they visit the crater of Mount Paektu, near Samjiyon. Mount Paektu has long been considered the spiritual birthplace of the Korean nation and is a place of pilgrimage for tens of thousands of North Koreans every year, who are trained from birth to revere their leaders. (Photo by Ed Jones/AFP Photo)

A bride and groom jump over a skipping rope as they pose during a wedding photo shoot at a park in Pyongyang on April 18, 2019. (Photo by Ed Jones/AFP Photo)

German field telegraph operators at work in Warsaw. (Photo by Hulton Archive/Getty Images). 1st October 1914

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

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)