A document shows that the Russian investigation team that came to Korea from May 31 to June 7 to conduct its own investigation into the sinking of the Cheonan concluded that the sinking resulted from an "indirect outside underwater explosion," but that the blast was more likely from a mine than a torpedo.
In particular, the Russian team raised doubts about the time of the explosion reported by South Korea's joint civilian-military investigation team, which announced that the blast to the Cheonan came from a North Korean torpedo attack at 9:21:58 p.m. on March 26. The Russian team's conclusion was based on factors such as the last time indicated on the Cheonan's closed circuit television footage, which was 9:17:03 p.m. on the night in question.
On Monday, the Hankyoreh acquired a document titled "Data from the Russian Naval Expert Group's Investigation into the Cause of the South Korean Naval Vessel Cheonan's Sinking," in which the Russian team stated, "The explosion time officially stated by South Korea [9:21:58 p.m.] does not coincide with the time of the last video footage taken on the day in question when the power current was cut off within the vessel [9:17:03 p.m.]." This statement hints that an uncontrollable situation may have arisen at least four to five minutes before the time announced by the South Korean team.
The Russian team also said that a sailor on board the Cheonan made a cell phone call at 9:12:03 p.m. notifying a Naval signalman that crew members were injured. "The record of this first communication does not accord with what was official stated by South Korea," the team said. This coincides with a July 8 Hankyoreh report stating that the Russian team had "detected the transmission of a distress signal at a time earlier than the time of the Cheonan explosion."
In response, the Ministry of National Defense explained that the CCTV time was some three minutes and 47 to 50 seconds off the actual time, but that it did not disclose this fact at the time because it might "give rise to unnecessary misunderstandings." The ministry also said, "Beyond what was already disclosed, there is no record at all of anything like a Cheonan crew member providing notification about injuries by cell phone."
The Russian team also raised questions about the so-called "No. 1 torpedo" fragment presented by the South Korean team as "conclusive evidence" of North Korean responsibility for the sinking. "While the torpedo fragment may have been made in North Korea, the characters written in ink do not conform to general standards" in terms of location and lettering, the Russian team said. The Russian team went to say, "Based on a naked-eye analysis of the torpedo fragment presented, one could believe that the fragment had been underwater for six months or more." Previously, the South Korean team announced that a naked-eye analysis of the degree of corrosion indicated that the torpedo debris had been underwater for around one to two months.
Regarding damage to the Cheonan's propeller screws, the Russian team wrote, "Since before the time of the disaster in question, all five of the right-side screw wings and two of the screw wings on the left had been damaged due to contact with the ocean floor." In short, the Russian team held that the screws became broken or bent due to contact with the ocean floor, which varies considerably from the official announcement by the South Korean team.
On its conclusions regarding the cause of the sinking, the Russian team wrote, "The claims that it was a non-contact external underwater explosion were borne out." At the same time, it conjectured that the accident occurred when "the vessel's propeller happened to get caught in a net as it was sailing through shallow waters near the coast, and as the vessel was trying to extricate itself to deep waters, its lower part struck a [mine] antenna and set off the triggering device."