(24.5.2010) If the boat was not sunk by an attack from the North, the remaining possibility is that an error occurred. I suspect that the US military had not informed the ROK that an American submarine was stationed underwater near Byaengnyeong Island. If the American submarine that sank at the third buoy was underwater for a long time, it follows that it did not participate in the joint exercise that day (it had other duties).

I think it likely that the US submarine, which was off the coast to the south of Byaengnyeong, happened to approach closer to the shore than expected and ROK forces, mistaking it for a North Korean submarine, fired. When the US submarine returned fire, both boats sank as a result of a friendly attack due to a misconception. The US submarine must have known of the approach of the Cheonan with the use of a passive sonar used for receiving communication. But if the American military was keeping the presence of the submarine secret from the ROK, then the US submarine could not communicate by radio with the Cheonan.

The Cheonan was attacked from the port side. The ROK authorities announced that the Cheonan at that time was heading northwest. If that is really the case, then the boat’s port faced the open sea. The American submarine underwater near the shore would have attacked from the island side, the reverse of the open sea side. This contradicts the above hypothesis. Except, in order to hide the friendly attack by the US military ship, the possibility exists that the ROK authorities announced the direction of the Cheonan in reverse. (If they announced that the Cheonan was attacked from the island side, then the North Korea attack theory would not be possible and the suspicion of a friendly attack would become stronger.)