On an alternative possibility, that of the Cheonan being sunk by a mine, he explained, "The laying of an influence mine is extremely difficult, and the explosive power of a mine is more than 5 times that of a torpedo. So, judging by the destroyed Cheonan, the possibility of this being the cause is very low." In any case, Lee is totally convinced by the marking, “1-beon” on the torpedo drive shaft, saying it is a normal thing in North Korea and represents irrefutable evidence of his nation’s culpability. He commented, “In North Korea, even torpedoes are repaired by hand. For maintenance, a torpedo needs to be disassembled then checked for defects, rust must be removed, and other maintenance done. When a torpedo is being disassembled, sometimes a part can be lost or confused with another part of another torpedo. That is why they mark them with numbers and assemble them accordingly. The same method is used when they repair the detonator on an influence torpedo. The torpedo detonator only weighs about three kilograms, yet still it is disassembled and reassembled. So, it must be numbered several times.”

Very interesting assertions ...