On March 26, 2010, the South Korean naval ship Cheonan sank in the Yellow Sea near the Northern Limit Line, and 46 sailors died. An international investigation concluded that a torpedo from a North Korean submarine caused the sinking. North Korea denied responsibility.
The Northern Limit Line is a maritime boundary drawn after the Korean War. North Korea does not accept it, and the area has seen several clashes.
The incident led to tensions and new sanctions and military measures, and it is a frequently cited case in studies of crisis management.
