In a photo taken on June 5, 2017 a traffic security officer stands on duty at an intersection in Pyongyang. Officially known as traffic security officers but universally referred to as traffic ladies, they are chosen for their looks in a society that remains traditionalist in many respects. They must leave the role if they marry, and have a finite shelf-life, with compulsory retirement looming at just 26. (Photo by Ed Jones/AFP Photo)

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.

In a photo taken on July 6, 2017 soldiers of the Korean People' s Army (KPA) watch a fireworks display as part of celebrations marking the July 4 launch of the Hwasong-14 intercontinental ballistic missile, in Pyongyang Fireworks lit up the sky over Pyongyang' s Juche Tower as North Korea celebrated its launch of intercontinental ballistic missile, a milestone in its decades- long weapons drive. On July 4 – the United States' Independence Day – it launched a Hwasong-14 rocket that analysts and overseas officials said had a range of up to 8,000 kilometres, which would put Alaska and Hawaii within reach. (Photo by Kim Won-Jin/AFP Photo)

Schoolchildren play music to entertain and inspire people on their way home from work Tuesday, March 29, 2016 in Pyongyang, North Korea. North Korea has called a 70-day loyalty drive areas of a major congress of the ruling party scheduled for early May and everyone from students to coal miners have been mobilized nationwide to demonstrate their devotion to the leadership. (Photo by Eric Talmadge/AP Photo)

A guard secures gates of a catfish farm visited by a group of foreign reporters in Pyongyang, North Korea April 17, 2017. (Photo by Damir Sagolj/Reuters)

A traffic police officer directs vehicles at a street junction during sunset in Pyongyang, North Korea, Thursday, August 25, 2016. (Photo by Dita Alangkara/AP Photo)

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

North Koreans perform during the “Arirang” Mass Games at the May Day Stadium in Pyongyang, as part of celebrations ahead of the 60th anniversary marking the end of the 1950-53 Korean War, in this photo taken by Kyodo July 22, 2013. (Photo by KYODO)