In this regard, Dr. Jong Chol Ho, a teacher of Kim Il Sung University, told KCNA:

According to the article, a physics professor of south Korea's Kyongsong University and a mechanical engineering doctor of Britain's University of Cambridge contended, in their joint paper contributed to an international scientific magazine, that the warship "Cheonan" might have collided with a submarine.

The scholars mentioned that the frequency spectrum of earthquake wave, registered in Paekryong Island at the time of the warship sinking, is similar to that of a 113 meter-long submarine's natural oscillation.

The "Cheonan", made with 1.2 cm-thick alloy of steel and aluminum, went sunken but the submarine, made with high-tensile steel 6 cm thick, was not likely to be damaged, they pointed out, adding that changed shape of the warship's hull was enough to prove the collision.

The paper recalled the fact that many groups of south Korea had called for a probe into the suspicious collision between "Cheonan" and a U.S. submarine involved in the war exercises around the area of accident.

The U.S. and the south Korean authorities should open to the public the truth about the "Cheonan" warship sinking case and reveal their dirty colors as a wrecker of peace.