The independent investigation into the sinking of the Cheonan has concluded that the vessel was sunk by an underwater explosion caused by a North Korean mid-sized torpedo containing 250 kg of high explosives.

Yoon Deok Yong, the chief of the joint civilian-military joint investigation team reported the results this morning in a long-awaited Ministry of National Defense press conference, confirming, “Our investigation has arrived at the conclusion that the Cheonan was sunk by an underwater explosion caused by a North Korean torpedo.”

Yoon concluded, “There is no other conclusion but to say that it was a torpedo fired from a small submarine. The Cheonan was sunk by the external, underwater explosion of a North Korean torpedo.”

“A pair of propellers, propeller motor and steering gear which were scattered around Baekryeong Island and subsequently collected by dredgers exactly correspond to the blueprints of a North Korean torpedo, ‘CHT-02D,’ which is contained in a booklet advertising North Korean weapons for export.”

The investigation team collected a 1.5m long fragment of a torpedo including a complete pair of propellers and a drive shaft, on which “1 beon” (“1번”) is marked in Korean.

The investigation team collected a 1.5m long segment of the torpedo including a complete pair of propellers, a fragment of another pair of propellers and a drive shaft, on which “1 beon” (“1번”) is marked in Korean.

Torpedo CHT-02D is a middle-sized torpedo which can carry 250kg of explosives, weighs 1.7 tons and is 21 inches in diameter.

Yoon explained, “On the inside surface of the rear part of the steering gear, ‘1 beon,’ which means No. 1, was found. This corresponds with the way North Korea marked torpedoes we collected before, and confirms that the parts were produced by North Korea.”

As a result of a computer simulation, he added, “We believe that between 200 and 300kg of explosives were detonated around six to nine meters underwater and around three meters to the portside from the center of the gas turbine room.”

He also explained, “A sentry on Baekryeong Island at the time of the explosion testified that he saw a 100 meter high white flash for two or three seconds, which is exactly the phenomenon which is caused by the column of water from an underwater explosion.”

Regarding the movements of submersibles which might have been responsible, Yoon explained, “Some small submersibles and a command ship supporting them left a North Korean naval base two or three days before the Cheonan attack and returned to base two or three days after it.”

“These results have been confirmed by the multi-nation coalition information analysis of five countries: the U.S., Australia, the U.K. and Canada,” he concluded.

The joint civilian-military investigation team consists of 25 experts from ten domestic professional institutes, 22 military experts, three lawmakers from related National Assembly committees and 24 foreign experts from the U.S., Australia, the U.K. and Sweden. The group was divided into four departments: forensic science, explosive pattern analysis, hull structure and data analysis.