The New York Times is reporting that the South Koreans are going to blame a North Korean torpedo for sinking a South Korean corvette on March 26, killing 46 sailors.
There's no firm evidence about where the torpedo came from, but it seems probable it was from a submarine. If so, this will be just the third sinking of a warship by a sub since World War II. (The others were the Argentine cruiser General Belgrano sunk in the Falklands War on May 2, 1982 and an Indian frigate sunk by a Pakistani sub on December 8, 1971.
Should be interesting to see how this develops.