The Sinking of ROKS Cheonan occurred on 26 March 2010, when Cheonan, a Pohang-class corvette of South Korea, carrying 104 personnel, sank off the country's west coast near Baengnyeong Island in the Yellow Sea, killing 46 seamen. The cause of the sinking is disputed.
A South Korean-led official investigation carried out by a team of international experts from South Korea, the United States, the United Kingdom, Canada, Australia, and Sweden presented a summary of its investigation on 20 May 2010, concluding that the warship had been sunk by a North Korean torpedo fired by a midget submarine. The conclusions of the report resulted in significant controversy within South Korea. Following the sinking, South Korea imposed sanctions against North Korea, known as the May 24 measures.
North Korea denied that it was responsible for the sinking. North Korea's further offer to aid an open investigation was disregarded. China dismissed the official scenario presented by South Korea and the United States as lacking in credibility. The results of an investigation by the Russian Navy were not made public. The United Nations Security Council made a Presidential Statement condemning the attack but without identifying the attacker.
Background
Baengnyeong Island is a South Korean island in the Yellow Sea, off the Ongjin peninsula in North Korea. It lies less than 10 miles (16 km) from the North Korean coast, and is over 100 miles (160 km) from the South Korean mainland. The island is to the south and west of the Northern Limit Line, the de facto maritime boundary dividing South Korea (ROK) from North Korea (DPRK).
The area is the site of considerable tension between the two states; although it was provided in the armistice agreement for the stalemate of the Korean War that the islands themselves belonged to the South, the sea boundary was not covered by the armistice, and the sea is claimed by the North.
The situation is further complicated by the presence of a rich fishing ground used by DPRK and Chinese fishing vessels, and there have been numerous clashes over the years between naval vessels from both sides attempting to police what both sides regard as their territorial waters. These have been referred to as "crab wars".
History of ship sinkings on both sides
In late May 2010, Bruce Cumings, a University of Chicago expert on Korean affairs, commented that the sinking should be regarded as part of long-running tensions in a naval no-man's land. He noted a confrontation in November 2009 in which several North Korean sailors died, and an incident in 1999 when 30 North Koreans were killed and 70 wounded when their ship sank.
In both incidents, the North Koreans were the first to open fire. In the 1999 incident the South Koreans escalated matters by initiating a campaign of boat 'bumping' in order to stop what the South saw as a violation of its maritime borders. Considering these previous incidents, Cumings said that the Cheonan sinking was "ripped out of context, the context of a continuing war that has never ended."
Military concerns
General Walter L. Sharp, Commander of the South Korea-U.S. Combined Forces Command at the time had, on 24 March, testified before the US House Appropriations Committee, in part, on the need to strengthen the ROK-U.S. alliance, the need for on-site advanced training of the Air Force, the need to improve the quality of life and provide tour normalization for troops serving one-year tours, planned relocation of bases, and the scheduled 2012 transition of Operational Control (OPCON) to ROK. He also warned of the possibility that North Korea could "even launch an attack on the ROK."
Sinking of Cheonan
On the night of the sinking, the U.S. and South Korean navies were engaged in joint anti-submarine warfare exercises 75 miles (121 km) away. This was part of the annual Key Resolve/Foal Eagle war exercise, described as "one of the world's largest simulated exercises", involving many U.S. and South Korean warships.
On Friday, 26 March 2010, an explosion was reported to have occurred near Cheonan, a Pohang-class corvette, near the stern of the ship at 9:22 pm local time (12:22 pm GMT/UTC). This caused the ship to break in half five minutes afterward, sinking at approximately 9:30 pm about 1 nautical mile (1.9 km) off the south-west coast of Baengnyeong Island.
Some initial reports suggested that the ship was hit by a North Korean torpedo, and that the South Korean vessel had returned fire. However, the South Korean Ministry of Defense stressed in the first press briefings after the sinking that there was "no indication of North Korean involvement". Cheonan was operating its active sonar at the time, which did not detect any nearby submarine. Several theories have subsequently been put forth by various agencies as to the cause of the sinking. Early reports also suggested that South Korean navy units had shot at an unidentified ship heading towards North Korea, but a defense official later said that this target may have been a flock of birds misidentified on radar.
The ship had a crew of 104 men at the time of sinking, and 58 crewmembers, including all 7 officers on board were rescued by 11:13 pm local time. The remaining 46 crew died.
The stern of Cheonan settled on its left side in 130-metre (430 ft) deep water, close to the coordinates at which the hull broke up, whereas the bow section took longer to sink, before settling, overturned, in water 20 metres (66 ft) deep, 6.4 kilometres (3.5 nmi) away, with a small part of the hull remaining visible.
Rescue efforts
Initially six South Korean navy and two South Korean coast guard ships assisted in the rescue as well as aircraft from the Republic of Korea Air Force. It was reported on March 27 that hopes of finding the 46 missing crew alive were fading. Survival time in the water was estimated at two hours and large waves were hampering rescue attempts. After the sinking, President Lee Myung-bak said that recovery of survivors was the main priority. Air was pumped into the ship to keep any survivors alive.
Over 24 military vessels were involved over the course of the search-and-rescue effort, including four U.S. Navy vessels: USNS Salvor, USS Harpers Ferry, USS Curtis Wilbur, and USS Shiloh.
On 30 March 2010 it was reported that one South Korean naval diver (ROKN UDT/SEAL CWO Han Ju-ho) had died after losing consciousness while searching for survivors, and another had been hospitalised.
On 3 April 2010, South Korean officials said that a private fishing boat involved in the rescue operations had collided with a Cambodian freighter, sinking the fishing boat and killing at least two people, with seven reported missing. The same day, the Joint Chiefs of Staff of South Korea said that the body of one of the 46 missing sailors had been found.
Later on 3 April 2010 South Korea called off the rescue operation for the missing sailors, after families of the sailors asked for the operation to be suspended for fear of further casualties among the rescue divers. The military's focus then shifted towards salvage operations, which were predicted to take up to a month to complete.
Recovery
On 15 April 2010, the stern section of the ship was winched from the seabed by a large floating crane, drained of water and placed on a barge for transportation to the Pyongtaek navy base. On 23 April 2010, the stack was recovered, and on 24 April the bow portion was raised. The salvaged parts were taken to Pyongtaek navy base for an investigation into the cause of the sinking by both South Korean and foreign experts.
The bodies of 40 personnel out of 46 who went down with the ship were recovered. Their bodies were laid to rest at the Daejeon National Cemetery.
Cause of sinking
Investigation
After raising the ship, South Korea and the United States formed a joint investigative team to discover the cause of the sinking. Later South Korea announced that it intended to form an international group to investigate the sinking including Canada, Britain, Sweden and Australia.
On 16 April 2010, Yoon Duk-yong, co-chairman of the investigation team, said "In an initial examination of Cheonan's stern, South Korean and U.S. investigators found no traces showing that the hull had been hit directly by a torpedo. Instead, we've found traces proving that a powerful explosion caused possibly by a torpedo had occurred underwater. The explosion might have created a bubble jet that eventually generated an enormous shock wave and caused the ship to break in two." Traces of an explosive chemical substance used in torpedoes, RDX, were later found in May 2010.
The Washington Post reported on 19 May 2010, that a team of investigators from Sweden, Australia, Britain, and the United States had concluded that a North Korean torpedo sank the ship. The team found that the torpedo used was identical to a North Korean torpedo previously captured by South Korea. On 25 April 2010, the investigative team announced that the cause of the sinking was a non-contact underwater explosion.
On 7 May 2010, a government official said that a team of South Korean civilian and military experts had found traces of RDX, a high explosive more powerful than TNT and used in torpedoes. On 19 May 2010, the discovery of a fragment of metal containing a serial number similar to one on a North Korean torpedo salvaged by South Korea in 2003 was announced.
In their summary for the United Nations Security Council, the investigation group was described as the "Joint Civilian-Military Investigation Group of the Republic of Korea with the participation of international experts from Australia, Sweden, the United Kingdom and the United States, and the Multinational Combined Intelligence Task Force, comprising the Republic of Korea, Australia, Canada, the United Kingdom and the United States," which consisted of "25 experts from 10 top Korean expert agencies, 22 military experts, 3 experts recommended by the National Assembly, and 24 foreign experts constituting 4 support teams".
Joint Civilian-Military Investigation Group (JIG) report
Summary
On 20 May the South Korean-led investigation group released a summary of their report in which they concluded that the sinking of the warship was the result of a North Korean torpedo attack, commenting that "The evidence points overwhelmingly to the conclusion that the torpedo was fired by a North Korean submarine." The inquiry also alleged that a group of small submarines, escorted by a support ship, departed from a North Korean naval base a few days before the sinking. The specific weapon used was alleged to be a North Korean manufactured CHT-02D torpedo, of which substantial parts were recovered. The torpedo utilizes acoustic/wake homing and passive acoustic tracking methods.
According to the Chosun Ilbo, South Korean investigators told their journalists that they believe that one or two North Korean submarines, a Yono-class submarine and the other a Sang-O-class submarine, departed a naval base at Cape Bipagot accompanied by a support ship on 23 March 2010. One of the submarines, according to the report, detoured around to the west side of Baengnyeong Island, arriving on 25 March 2010. There, it waited about 30 metres (98 ft) under the ocean's surface in waters 40 to 50 metres (130 to 160 ft) deep for Cheonan to pass by.
Investigators were reported to believe that the submarine fired the torpedo from about 3 km (1.9 mi) away, timed for a period when tidal forces in the area were slow. The North Korean vessel returned to port on 28 March 2010. Such detailed information on the North Korean submarine movements, and attack position, was not in the official summary or final report.
Simulations indicated that 250 kg (550 lb) of TNT equivalent explosive at 6 to 9 metres (20 to 30 ft) depth, 3 metres (9.8 ft) to the port of the center line, would result in the damage seen to Cheonan.
The torpedo parts recovered at the site of the explosion by a dredging ship on 15 May which include the 5×5 bladed contra-rotating propellers, propulsion motor and a steering section, was claimed to match the schematics of the CHT-02D torpedo included in introductory brochures provided to foreign countries by North Korea for export purposes. An incorrect, though similar, torpedo schematic had by mistake been shown at the televised RIG briefing for comparison with the recovered parts. The correct schematic has never been made public.