North Korea says its new submarine has nuclear attack capabilities after years of development. Leader Kim Jong Un described the step as crucial in his efforts to build a nuclear-armed navy to counter the United States and its Asian allies. The North’s official Korean Central News Agency said the vessel, named “Hero Kim Kun Ok," is designed to launch tactical nuclear weapons from underwater. The agency did not specify the number of missiles it could carry and fire. In July, the U.S. docked a nuclear-capable ballistic missile submarine in South Korea for the first time since the...