Members of the public admire trees displaying their autumn colours at the Royal Horticultural Society Garden Wisley on October 26, 2011 in Wisley, England. Many deciduous trees have now changed colour as they begin to shed their leaves for Autumn. An extended period of leaf colour change has come about this year due to a warm, dry Spring prompting an early growth spurt and a premature colour change. (Photo by Oli Scarff/Getty Images)

North Koreans who signed up to join the army train in the midst of political tension with South Korea, in this undated photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang August 23, 2015. Top aides to the leaders of North and South Korea resumed talks on Sunday after negotiating through the night in a bid to ease tensions involving an exchange of artillery fire that brought the peninsula to the brink of armed conflict. (Photo by Reuters/KCNA)

In this Friday, January 6, 2017, photo, a North Korean woman working at the Kim Jong Suk Silk Mill looks up from her workstation in Pyongyang, North Korea. The silk mill, named after North Korean leader Kim Jong Un's grandmother, is where 1,600 workers – mostly women – sort and process silkworms to produce silk thread that officials at the Pyongyang factory say is made into roughly 200 tons of silk a year. (Photo by Wong Maye-E/AP Photo)

Two pins featuring former North Korean leader Kim Il Sung wearing different facial expressions are displayed in a glass case of Thomas Hui at his apartment in Hong Kong, China April 11, 2016. Collector Thomas Hui, 37, a former bank employee in Hong Kong, who is fascinated by North Korean pins and badges, has gathered over 100 featuring former leaders Kim Il Sung and Kim Jong Il, and has been buying and trading these Communist accessories since 2008. (Photo by Bobby Yip/Reuters)

An attendee takes a selfie at KCON USA, billed as the world's largest Korean culture convention and music festival, in Los Angeles, California on August 11, 2018. K-pop acts sing or rap in Korean, often with snippets of English. On the Web, where K-pop fandom thrives, many music videos include subtitles. (Photo by Mike Blake/Reuters)

An F/A-18 Hornet assigned to Strike Fighter Squadron One Five One (VFA-151) emerges from a cloud created when it broke the sound barrier in the skies over the Pacific Ocean, July 7, 1999. (Photo by John Gay/US Navy)