Update on the Cheonan

South Korea has reportedly ruled out a North Korean attack as the cause of the sinking of the Cheonan.

Initial speculation that North Korea might have sunk the ship had spooked Wall Street on Friday. Share prices dipped partly on geopolitical concerns, and the won dropped against the dollar.

“Given the investigations by government ministries so far, it is the government’s judgment that the incident was not caused by North Korea, although the reason for the accident has not been determined yet,” a senior government official was quoted as saying by Yonhap news agency.

A Reuters reporter on Baengnyeongdo island near where the ship sank said about 10 navy and coastguard vessels, along with divers, were searching the area and the wreckage.

MBC television quoted defense ministry sources as saying they were investigating whether it was the result of an explosion on board the vessel.

Presidential Blue House spokeswoman Kim Eun-hye earlier said there had been no unusual movements by North Korea, which has a million-strong military, much of it near the heavily armed border that has divided the Korean peninsula for more than half a century.

The defense ministry said 58 of the 104 crew on board had been rescued and Yonhap quoted navy officials as saying several had died. It was later quoted as saying 46 were still missing.

Mine, rock, and accidental internal explosion seem to be the leading candidates, as it appears that torpedo has been ruled out. A old stray mine is a possibility; a newer North Korean mine would be much more of a problem, but then you’d expect that the North Koreans would have been poised in some way to react to the entirely predictable sinking of a South Korean ship if they’d laid a minefield in the disputed area. Accidental internal explosion aren’t exactly common, but they do happen.