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)

North Korean leader Kim Jong Un (front) stands on the conning tower of a submarine during his inspection of the Korean People's Army (KPA) Naval Unit 167 in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang June 16, 2014. (Photo by Reuters/KCNA)

Women wearing traditional dresses with pins of pictures of former North Korean leaders Kim Il Sung and Kim Jong Il welcome foreign reporters on a government organised visit to the Kim Jong Suk Pyongyang textile mill in Pyongyang, North Korea May 9, 2016. (Photo by Damir Sagolj/Reuters)

Participants from a North Korea military band perform during the Spasskaya Tower international military music festival in Red Square in Moscow, Russia, Friday, August 23, 2019. (Photo by Alexander Zemlianichenko/AP Photo)

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)

North Korean leader Kim Jong Un (3rd R) and wife Ri Sol Ju (4th L) enjoy an art performance given by the Chongbong Band to mark the 70th anniversary of the founding of the Workers' Party of Korea (WPK) in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang on October 19, 2015. (Photo by Reuters/KCNA)

North Korean youngsters sing and play accordions to entertain foreign visitors including United Nations Secretary General Kurt Waldheim, who visited Pyongyang, May 4, 1979. Visitors report music education in North Korea begins at an early age and is taken seriously by children and adults. (Photo by Peter Arnett/AP Photo)

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)