‘External Explosion Likely Caused Sinking’

A civilian-military joint investigation team said yesterday that an external explosion in the left side of the naval patrol ship Cheonan likely caused the vessel to sink.

The team secured and are analyzing broken pieces of the vessel that could give clues on the cause of the explosion that split the ship in half.

Yoon Duk-yong, co-leader of the investigation team and an honorary professor at Korea Advanced Institute of Science and Technology, or KAIST, said, “After the probe into the cut part and the inside and outside of the ship, we concluded that the possibility that an external explosion occurred is very high.”

“The results of the investigation into the waters where the vessel submerged and the probe into the inside of the ship show a low possibility of a collision with a reef or metal fatigue of the ship.”

He added, “The hull and steel plates of the bottom of the stern were bent inward due to pressure from the left, and the right side of the stern was damaged and bent outward.”

This means the explosion occurred under the left side of the stern and the force of the explosion spread to the right.

“Seeing it from the right makes it appear that the explosion occurred on the right side of the ship, but experts say the damage (on the right side) was caused by an external explosion occurring on the left side,” Yoon said.

On the possibility of a torpedo explosion creating the bubble jet effect, he said, “A torpedo was possible but we also reviewing the possibility of a bubble jet torpedo attack.”

This means the investigation team puts more weight on the theory of the bubble jet torpedo explosion, which tears a ship apart by creating powerful gas bubbles.

Park Jung-yi, co-leader of the investigation team and head of the military capability improvement team at the Joint Chiefs of Staff, said, “We discovered broken pieces that can provide clues on the cause of the vessel’s sinking and analysis is underway.”

Park did not say, however, whether the pieces were part of the hull or shrapnel.

A high-ranking military official also told The Dong-A Ilbo over the phone, “We’ve secured a number of iron pieces and are comparing them to shrapnel of torpedoes and mines of the South Korean military.”

Separately, a Seoul official stressed the participation of Swedish officials in the investigation, saying, “The participation of a member country of the Neutral Nations Supervisory Commission, which deals with violations of the Korean War armistice by either Korea, will prepare for the possibility of North Korea’s involvement in the incident.”

srkim@donga.com mhpark@donga.com