|Speculations vary on cause of ship sinking|
Speculations have been rampant as to the cause of the sinking of a South Korean naval ship in waters near the disputed Yellow Sea border with North Korea on Friday night.
South Korean officials remain cautious, saying the exact cause of the explosion that sunk the 1,200-ton vessel can only be determined after the sunken ship is salvaged. The salvage process may take at least 20 days, military officials say, noting that it took 17 days to salvage a 130-ton vessel struck in a surprise attack by North Korea in 2002.
After visiting the disaster site Saturday, Defense Minister Kim Tae-young told reporters that the government is "yet to track down the exact cause behind the tragedy," adding that making predictions is "meaningless in this situation."
The official explanation that has been made so far by the military is that an unidentified explosion punctured a hole in the rear lower deck of the vessel, shutting off the engine and taking the ship down in less than three hours.
The slow work on finding the cause of the tragedy that left 46 of the ship's 104 sailors still missing, however, has stirred a wide range of speculations as to what caused the vessel to sink.
Experts speculate on largely three possible causes - an explosion within the ship due to internal defects or malfunctioning, accidental collision with a reef or other objects, or an attack from an outside force including the North Korean navy.
The possibility of an internal cause - such as an explosion of parts near the rear hull of the vessel where the explosion ripped a hole - appears to be very low, according to an expert.
"Personally, I think the possibility of an internal defect or malfunctioning is very low," said Kim Tae-woo, vice president of the Korea Institute for Defense Analyses.
"I have never heard of any navy vessel explode by itself so far, although it is too early to make presumptions when the government is still looking into possible causes."
Should it be an internal explosion, former crewmembers of the Cheonan have reportedly raised the possibility of mishandling of depth charges or other explosives that are kept in the rear end of the vessel.
The ship was carrying gunpowder and explosives, so a collision with an outside object could easily have caused an explosion.
But observers do not put much weight on the likelihood of a collision with a rock as the South Korean navy is largely familiar with the geographical features of the area where it often engages in training or patrol activities.
That leaves the possibility of the ship hitting some other object including floating or submarine mines that may have drifted from up north or being attacked by an outside force, most likely to be North Korean torpedoes. A submarine mine sticks to the hull of a ship like a magnet when a vessel passes above it.
Both South and North Korea placed floating or submarine mines near the Northern Limit Line, the de facto sea border.
A survivor from the sunken ship on Saturday raised the possibility of the 1,200-ton vessel sinking due to an attack from an outside force.
"There is no possibility whatsoever that the ship sank due to an internal explosion or a collision with a reef. I guarantee that," a navy lieutenant was quoted as saying by participants in a briefing session organized by the Navy's Second Fleet Command in Pyeongtaek, Gyeonggi Province - the home port of the ill-fated ship.
"Another cause could be an attack from an outside force and that is not exact as of yet. The military is currently conducting an investigation and I am not in a position to comment on that," he added.
A close observation of the hole would reveal whether the explosion occurred internally or externally. Divers had difficulty approaching the sunken ship on Saturday and yesterday due to high waves and strong wind in the area.
Some U.S. experts said Saturday sea mines might have caused the tragic sinking of the South Korean ship, dismissing concerns over possible North Korean involvement.
"I doubt that North Korea was involved in the incident," said John Feffer, co-director of the Foreign Policy in Focus program at the Institute for Policy Studies. "It didn't seem to involve any artillery fire from the North."
Feffer disagreed with the assumption that North Korea attacked the South Korean naval vessel, noting this incident is different from the previous clashes that involved fishing boats of the two Koreas crossing their sea border.
"There have been naval clashes between North and South in the past, but these have usually involved rising tensions, warnings, fishing boats crossing the NLL," he said. "But this was, as far as we know, a surprise. And there was no larger reason why the North might engage in such a surprise attack."
North Korea has long defied the NLL, the de-facto sea border drawn by the U.S.-led United Nations Command after the 1950-1953 Korean War, demanding the line be redrawn further south.
Bruce Klingner, senior research fellow at the Heritage Foundation, described the unexplained explosion as "an oddity in an era of sophisticated ships and communication," raising a sea mine as a possible cause.
"Although initial media reports suggested a North Korean torpedo as the cause, that interpretation now appears to be the result of overeager reporters," he said. "Seoul is now downplaying the likelihood of North Korean involvement in the explosion and sinking. A survivor of the sinking insists there was no onboard explosion, leading to speculation the cause was a naval mine, either South Korean or one that had drifted from the North."
Klingner, however, would not dismiss the chance of North Korea's involvement, pending the outcome of the ongoing investigations.
"Concerns over North Korean involvement remain, however, since the sinking occurred near the disputed maritime border which was the site of clashes in 1999, 2002 and 2009," he said.
"Pyongyang's return to more belligerent rhetoric was cited as cause for concern by the U.S. Pacific Command on the day before the sinking."
By Kim So-hyun and news reports