JR Potts, AUS 173d AB (Updated: 6/29/2016):
Cheonan Mission Effectiveness
The Cheonan's primary mission was coastal patrol, utilizing her 9.5ft draught to good effect in close inshore patrol work near the North Korean coast. Additionally, her compact design offered a three-pronged multi-mission capability - anti-submarine, anti-ship and anti-aircraft. Her anti-submarine warfare (ASW) capability included sensors to find enemy submarines and Mk 46 type homing torpedoes or the Mark 9 depth charges to be used in anger if warranted. For anti-ship actions, PCC-772 fielded 2 x Harpoon anti-ship missiles, with launchers placed on the lower aft deck, in addition to 2 x 76mm OTO Melara main guns - one held forward and one held aft. For close-in, anti-aircraft protection, 2 x 40mm Bofors cannons were positioned just above the 76mm main guns. Cheonan, and her sister ships, were powered by 2 x MTU diesel generators producing 6,260 shaft horsepower. The engines drove 2 x shafts through the installed gearboxes allowing her to make 30 knots in ideal conditions. Onboard accommodations were adequate for 95 sailors and 10 officers as well as machinery areas and control centers.
The Cheonan and the Yellow Sea
The ROKS Cheonan (PCC-772) suffered minimal damage on the aft deck during the First Battle of Yeonpyeong in 1999 - a limited conflict between North Korea and South Korea in the oft-disputed area of the Yellow Sea. The Cheonan and other corvette ships continued to patrol the Yellow Sea, searching for enemy submarines attempting to penetrate South Korean waters. The Yellow Sea became one of the most dangerous bodies of water in the world, heavily patrolled by two warring sides since the end of the Korea War (1953). North Korean submarines were known to regularly enter the disputed Yellow Sea, looking for South Korean ships and areas of the South Korean defense that they could possibly exploit.
At the beginning of 2010, Cheonan had been in Republic of Korea Navy service for some 21 years and was scheduled to be decommissioned in 2019. On March 26th, 2010, she was patrolling the Yellow Sea as normal, this about one mile off the coast of Baengyeong Island near the boundary line between the North and South. At 9:30 PM local time, an explosion took place in the aft section of the ship. Captain Choi Won il said the ship broke in two and the stern sank in minutes. The sea was frigid and it was estimated that survivors would only last for a matter of hours in the cold heavy waters. Cheonan's radio room got off the requisite S.O.S. with the latitude and longitude of the ship's current location. At the time of the accident, the Cheonan reported a crew of 104 men. Six ROK ships were promptly dispatched to the rescue area along with a number of aircraft for aerial support.
As the rescue operation began, 58 Cheonan crew members were picked up and the search for the remaining 46 continued. The vessel sank in just 45 meters of water with a portion of the hull remaining visible just above the water. It was presumed possible that some men were still alive, trapped in sections of the ship below the water, so naval divers were sent to attempt a rescue. Additional ships arrived to help including US support in the form of the USNS Salvor (a salvage ship), the USS Harpers Ferry (an LSD dock landing ship) and the USS Shiloh (a Ticonderoga-class guided-missile cruiser) - the latter to provide an expanded envelope of protection for the remainder of the operation.
The Rescue Turns to Salvage
On March 27th, hope for finding any more of the Cheonan crew alive was slipping - the operation now involving over 25 ships. Several incidents in the operation itself led to the death of one South Korean diver and the injury of another. A private fishing boat that was aiding in the rescue collided with a nearby Cambodian freighter and sunk, killing two onboard with another seven crew members going missing. Fearing more causalities, the ROK government called off the rescue on April 3rd and shifted efforts to salvaging the vessel. A large floating crane was towed to the site and, on April 15th, the stern section was raised and recovered. The rest of the ship was raised by another crane on April 25th and the vessel was taken to a port near Seoul for further investigation into the cause of the loss. In the whole of the extensive recovery operation, only a single body of the lost 46 was recovered.
The Verdict is In
On April 25, 2010 a news conference was held in Seoul and the defense minister Kim Tae-Young said the proposed "bubble jet" theory was supported by the investigation. The theory centered around a non-contact explosion by a torpedo just under the hull. The resulting explosion was believed to have broken the ship in two. An international commission looking into the sinking of the Cheonan provided its findings on May 20th, 2010, and indicated the ship was sunk by a North Korean CHT-02D torpedo. The findings were made when the area was dredged and torpedo parts were recovered at the site of the explosion, this occurring on May 15th. Found were 5x5 bladed contra-rotating propellers, a propulsion motor and parts of a steering section - all matching the CHT-02D type torpedo used by the North. Markings in the Hangul language, found inside the end of the propulsion section, were also consistent with markings found on North Korean torpedoes in the past. It is suspected a Yeono-class submarine was used to deliberately sink the Cheonan.
On May 20th, 2010, South Korean officials issued a formal report blaming North Korea for the March 26th, 2010 sinking of the Cheonan. In an expected rebuttal, a spokesman for the North Korean DPRK, National Defence Commission, issued a statement that repudiated the claim, stating that the South Korean's are a group of traitors and the joint investigation is based on sheer fabrication solely for the purpose of indicting North Korea on any charge it could find.