North Korea arrests fourth official following serious accident at launch of Chongjin warship, as Kim Jong Un denounces 'criminal act'

<p>Following a serious accident at the launch of the Chongjin warship, North Korea has arrested four officials, including Ri Hyong Son, believed responsible for the incident. Kim Jong Un condemned the event as a 'criminal act'. Although a crack in the bottom of the ship was initially reported, a later inspection confirmed that this was not the cause of the incident. Analysts suggest the ship may have been built with Russian help. North Korea has launched a detailed investigation into the reasons behind the accident.