Amid rampant speculation that the Navy corvette Cheonan sank due to a torpedo attack by a North Korean submarine or semi-submersible, there are reports that South Korean and U.S. intelligence agencies detected a submarine disappearing and reappearing at a North Korean submarine base on the west coast not far from the site of the wreck around Friday, the day the ship sank.
A South Korean government source said on Tuesday, "Scrutiny of pictures taken by U.S. spy satellites reveals one submarine in North Korea's Sagot naval base some 50 km away from Baeknyeong Island disappeared for a few days before Friday last week and returned to base later."
The source said North Korean submarines or semi-submersibles "occasionally disappear from the base and come back, so it's difficult at the moment to relate this to the sinking of the Cheonan. We are currently establishing the exact circumstances."
Defense Minister Kim Tae-young on Monday told the National Assembly's Defense Committee that North Korean semi-submersibles can fire two torpedoes.
The Sagot base is home to North Korea's core west coast naval forces including some 20 submarines and semi-submersibles.