South Korea's Amry Special Warfare Command (SWC) soldiers aim their machine guns in a frozen river during a winter exercise in Pyeongchang, South Korea, Thursday, January 8, 2015. About 200 SWC soldiers participated in this routine two-week winter drill. (Photo by Ahn Young-joon/AP Photo)

North Koreans perform during a mass game of “The Land of the People” at the May Day Stadium in Pyongyang, North Korea, Tuesday, June 25, 2019. (Photo by Jon Chol Jin/AP Photo)

In this Friday, August. 17, 2018, photo, a North Korean waitress prepares to serve dinner to Chinese tourists at the Pegaebong hotel in Samjiyong in North Korea. Chinese businesspeople and tourists are once again flowing over the borders – several large tourist groups were in Samjiyon last week – and South Korean officials are seriously considering ways to help the North improve its roads and railways. (Photo by Ng Han Guan/AP Photo)

A member of North Korean military holds flowers to be laid at the bronze statues of the late leaders Kim Il Sung and Kim Jong Il at Mansu Hill Grand Monument in Pyongyang, North Korea, Monday, December 17, 2018. North Koreans are marking the seventh anniversary of the death of leader Kim Jong Il with visits to the statues and vows of loyalty to his son, Kim Jong Un. (Photo by Dita Alangkara/AP Photo)

A subway worker walks away after a train departed the station in central Pyongyang, North Korea May 7, 2016. (Photo by Damir Sagolj/Reuters)

Two railway workers chat in front of a flower mural inside a subway station visited by foreign reporters during a government organised tour in Pyongyang, North Korea October 9, 2015. (Photo by Damir Sagolj/Reuters)

A woman surrounded by South Korean national flags set up to celebrate the 66th Independence Day on August 15, 2011 in Seoul, South Korea. Korea was liberated from Japan's 35-year colonial rule in 1945. (Photo by Chung Sung-Jun/Getty Images)

A South Korean soldier wear North Korea's military uniform, acting as North Korean soldier during an anti-terror and anti-chemical drill session held as part of the 2011 Ulchi Freedom Guardian (UFG) event on August 17, 2011 in Seoul, South Korea. The 11-day UGC, which features drills including the handling of chemical and biological attacks, is a regular joint exercise between US and South Korean troops to prepare for potential emergencies on the Korean Peninsula. (Photo by Chung Sung-Jun/Getty Images)