Kim Jong Un vows to expand his nuclear arsenal by building nuclear submarines, underwater missiles and warheads that can hit American cities Admin North Korea, Nuclear - Weapons - Threats - War, Wars & Rumours of Wars January 9, 2021 1 Minute Kim Jong Un vowed to expand North Korea’s nuclear arsenal during a key meeting of the ruling party this week, boasting that nuclear submarines, underwater missiles and warheads that could reach American cities were all under development, state media reported. Share this:Share on TumblrTweetEmailLike this:Like Loading... Published January 9, 2021