An international investigative team released new details this week to bolster earlier conclusions that the South Korean warship Cheonan was sunk by a high-tech North Korean torpedo that exploded beneath the ship.
The South Korean government-led Joint Civilian-Military Investigative Group, or JIG, released the report in response to claims by two U.S. professors who charged that Seoul fabricated evidence linking North Korea to the sinking.
“The … Cheonan was split and sunk due to shockwave and bubble effect generated by a non-contact underwater explosion” at a depth of 20 to 30 feet, the JIG stated. In the group were 74 civilian and military analysts from South Korea, the United States, Australia, Britain and Sweden.
The JIG report disclosed that a shock wave from the torpedo explosion split the hull below the turbine engine room. The report included photos showing bottom plates bowed inward toward the ship, a sign of an external blast and not an internal explosion.
Survivors suffered broken bones, which the report said indicated a “bubble jet effect generated by an underwater explosion.”
Evidence of the North Korean torpedo included a Korean-language “No. 1” inscribed on the propulsion section of the torpedo that was recovered.
“A detailed analysis of the [No. 1] inscription was conducted using a spectroscope,” the report said. “This analysis found that the inscription is marked on anti-corrosive paint - which was applied on the iron part of the propulsion motor and has a color similar to stainless steel.”
The report said the number was not destroyed because the explosion’s heat did not damage that part of the torpedo.
The report also challenged the findings of the two professors, who claimed that their chemical analysis of aluminum residue suggested that an explosion was “fabricated.”
South Korean-born professors Seunghun Lee of the University of Virginia and J.J. Suh of Johns Hopkins University’s School of Advanced International Studies charged that the earlier JIG investigation failed to prove that an explosion occurred outside the ship or that it was caused by a torpedo made in North Korea.
Mr. Lee and Mr. Suh could not be reached for comment.
Rear Adm. Thomas J. Eccles, the senior U.S. official in the investigative group, was unavailable for comment.
However, Adm. Eccles told the Los Angeles Times that investigators ruled out a ship grounding, an internal explosive and an undersea mine as causes of the sinking. The team concluded that a bubble-jet torpedo created a blast that did not leave normal signs of an explosion, he said.
Adm. Eccles said the pattern of damage to the Cheonan was “exactly aligned” with the high-tech torpedo that is designed to dive underneath a ship, detonate and use the energy of the explosion to create a high-impact bubble that expands and contracts.
The bubble-jet torpedo is designed to “break the back of the ship,” he said.
The U.S. government has asserted that the ship was hit in an unprovoked attack from a North Korean submarine, although a U.N. statement on the sinking did not mention North Korea by name.
Deputy Secretary of State James Steinberg said Tuesday during remarks to a conference at the Nixon Center that large-scale U.S. and South Korean naval exercises aimed at North Korea were conducted because of China’s failure to condemn the attack.
“China is suffering the indignity of exercises close to its shores, and though they are not directed at China, the exercises are a direct result of China’s support for North Korea and unwillingness to denounce their aggression,” Mr. Steinberg said.
Based on the JIG conclusions, the Obama administration plans to impose new economic sanctions against Pyongyang.
North Korea’s government has denied it carried out the March 26 attack on the ship near the South Korean Baengnyeong Island, close to northern sea limit line with North Korea on the west coast of the Korean Peninsula.