His father was afraid to fly, but North Korean leader Kim Jong Un has taken to the skies, building a series of small runways long enough to land light, private aircraft next to some of his palaces, satellite imagery shows.

Construction on Kim's personal landing strips began in 2014 and some were completed as recently as last month, according to satellite imagery identified by Curtis Melvin of the U.S.-Korea Institute at Johns Hopkins University in Washington.

"These runways are located near Kim family compounds — sometimes within the security perimeters — and next to private train stations that were used by Kim Jong Il," Melvin told Reuters.