"North Korea may have intentionally floated underwater mines to inflict damage on us," he said.
A mine placed by North Korea during the 1950-53 Korean War may also have struck the ship, he said.
Or it could have been an accident. I've speculated that it could have been a mine or accident--or a torpedo, even.
If North Korea was trying to make a point, they've been very quiet since the incident.
Or the message might just be meant for their own leadership to show that North Korea will strike if necessary.
Or the North Koreans just wanted to kill.
Or, as is quite possible, it is all just an ill-timed accident. Examining the hull should provide the clues, I dare say.