Something is moving in Kim's secret shipyard: North Korea's lone missile sub vanished into drydock?

Commercial satellite imagery shows North Korea’s sole Gorae-class ballistic-missile submarine, the 8.24 Yongung, in drydock at the Sinpho South Shipyard, prompting speculation that it is undergoing refurbishment or upgrades. The nature and scale of the work are not publicly known. Separately, North Korea has displayed an under-construction 8,700-ton nuclear-powered “strategic guided-missile submarine,” which state media says forms part of Kim Jong-un’s long-term naval-modernisation programme. It has not been launched or confirmed operational.