In a study paper titled "What caused the sinking of Cheonan warship in actuality?" which he jointly contributed to an international scientific magazine together with a researcher of Cambridge University, he claimed that there is high possibility that the warship was sunken by collision with a submarine.

Refuting this, an administrative official of Chongwadae of south Korea, said the depth of the waters where the warship was sunken was only 47 meters, too low for any U.S. submarine to operate, adding that even though the problematic submarine had risen to surface there, it could never have hit the middle part of the warship in such a depth.

Those of the "Saenuri Party" were busy terming the claim "a false rumor."

As regards the comment, Kim queried why the 30 meter high submarine can not operate in 47 meter depth.

The fact that the bow of the warship turned 200 degrees when sinking clearly proved its collision with a submarine, he added.

He deplored the political camp disregarding science.

He also blamed the chief of the joint investigation group for taking the lead in checking the probe into the truth behind the disaster.