A soldier stands guard on the aircraft park of the Pyongyang Airport on April 3, 2011 in Pyongyang, North Korea. Pyongyang is the capital city of North Korea and the population is about 2,500,000.

North Korean traffic police women chat next to a residential building while off duty Tuesday, October 18, 2016, in Pyongyang, North Korea. (Photo by Wong Maye-E/AP Photo)

North Korean defectors, now living in South Korea, prepare to release balloons carrying propaganda leaflets denouncing North Korea's late leader Kim Jong-Il at Imjingak, near the Demilitarized zone (DMZ) separating South and North Korea on December 28, 2011 in Paju, South Korea. (Photo by Chung Sung-Jun/Getty Images)

North Korean leader Kim Jong Un smiles as he attends a flight training session by female fighter pilots Jo Kum Hyang and Rim Sol in this undated photo released by North Korea's Korean Central News Agency (KCNA) on June 22, 2015. (Photo by Reuters/KCNA/Antara Foto)

North Korean leader Kim Jong Un is hugged by children during his visit to Samjiyon County in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang November 28, 2016. (Photo by Reuters/KCNA)

A woman guards stand at the gate of a cosmetic factory during a government organised visit for foreign reporters ahead of 70th anniversary of North Korea's foundation in Pyongyang, North Korea on September 8, 2018. (Photo by Danish Siddiqui/Reuters)

North Korean soldiers march during a military parade marking the 105th birth anniversary of the country's founding father Kim Il Sung in Pyongyang, North Korea, April 15, 2017. (Photo by Damir Sagolj/Reuters)

A man impersonating North Korean leader Kim Jong Un gestures as he stands before North Korean cheerleaders attending the Unified Korean ice hockey game against Japan during the Pyeongchang 2018 Winter Olympic Games at the Kwandong Hockey Centre in Gangneung on February 14, 2018. (Photo by Yelim Lee/AFP Photo)