South Korean rescue members wearing chemical protective suits walk past a monster character (R) during an anti-terror drill as part of a disaster management exercise at the COEX shopping and exhibition center in Seoul on May 20, 2016. South Korea is holding its 2016 Safe Korea anti-disaster exercise this week against terrorist threats and natural disasters. (Photo by Jung Yeon-Je/AFP 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)

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)

KARA perform on stage during their first solo concert KARASIA at Olympic gymnasium on February 18, 2012 in Seoul, South Korea. (Photo by Chung Sung-Jun/Getty Images)

Performers of Everland Amusement Park present the part of Christmas Fantasy in downtown of Myundong in Seoul, South Korea on December 3, 2019. (Photo by Seokyong Lee/Penta Press/Rex Features/Shutterstock)

Participants play with water guns during the Sinchon Water Gun Festival in Seoul, South Korea, July 9, 2016. (Photo by Kim Hong-Ji/Reuters)

A man wearing a Guy Fawkes mask enjoys a ride on a 350-meter (1148 feet) long water slide during 2015 City Silde Festa in central Seoul, South Korea, July 19, 2015. A 350 meter-long waterslide has been installed in downtown of Seoul, the longest waterslide to be recorded in Korea, according to local media. (Photo by Kim Hong-Ji/Reuters)

Members of team China perform during the Artistic Swimming Team Free Final at the FINA Swimming World Championships in Gwangju, South Korea, 19 July 2019. (Photo by Antonio Bat/EPA/EFE/Rex Features/Shutterstock)