By Tong Kim

While no hard evidence has yet been discovered for the explosion that sank the ROK Navy corvette Cheonoan many now point to North Korea as the culprit. There is plenty of circumstantial evidence to support the accusation. When the investigators determined that the ship's sinking was caused by a ``non-contact underwater explosion'' of a torpedo, North Korea instantly became the prime suspect, because ``no other country would have done it.''

North Korea has a record of committing violent acts against the South, including two attempts to kill South Korean presidents, first in 1968 and again in 1983, and the midair explosion of a Korean Airliner in 1987. However, in a civilized justice system, a record of past crimes is not accepted as evidence against the accused.

Physical evidence would consist of scraps of the exploded torpedo and the identification of the shooter ― either a torpedo boat or a submarine, or the installer of the explosive, if it was a timed mine. A piece of aluminum metal that was found in the retrieved vessel may not be sufficient evidence even though the metal is alien to those used in the construction of the ship.

It would be difficult, if not impossible, to collect all pieces of objective forensic evidence to deliver a definitive guilty verdict on the North as the real criminal beyond reasonable doubt. As the burden of proof rests with the South ― who does not even have any dialogue with the North, the task of winning the criminal case would be even more difficult.

On the other hand, it is still important to discuss the possible motivation for the suspected crime despite there being no scientific way of doing so. Nevertheless, some possible theories are as follows:

Theory 1, the North Koreans wanted to attract the attention of the Obama administration, which refused to engage them unless they return to denuclearization talks. Proponents of this theory point out that the North Koreans have caused trouble mostly when they were not engaged by Washington. (This group even calls for a rethinking of the current U.S. policy to prevent similar future incidents.) This theory ignores the North's consistent strategy that it pursues a provocative military path as a means of survival and that they did not develop nuclear weapons for attention getting or for a negotiating leverage.

Theory 2, the North wanted to avenge its November 2009 defeat in a naval clash, in which a North Korea ship was heavily damaged with the loss of one North Korean sailor. This theory cites an earlier naval clash in 2002, which was interpreted as revenge by the North. The North had suffered a serious defeat and the loss of 30 lives and a boat in 1999. However, this retaliation is believed to have been initiated by a North Korean navy commander, without a direct order from Dear Leader Kim Jong-il. (Director of the Cheong Wa Dae situation room at the time of the incident recently revealed that the Kim Dae-jung government immediately protested the incident to the North Korean leadership, who in turn explained that it was done on a lower level.) But, Kim rarely admits responsibility for an attack against the South.

Theory 3, the North had needed to create tension for its internal political agenda, especially to solidify support for a second power succession to Kim Jong-un. This theory also lacks plausibility. Since North Korea is an autocratic dynasty, it should be no surprise that Kim Jong-il's son will be enthroned. Whether the transition will take place in 2012 is not clear. What is clear is that the elder Kim wants to improve the North's economy to a minimum sustainable level, in order to announce that the DPRK has entered the ``gate to a strong and prosperous state'' in commemoration of the 100th anniversary of Great Leader Kim Il-sung's birthday.

Theory 4, the North Korean military hardliners, taking advantage of the declining power of the ailing Kim Jong-il, attacked the Cheonan to secure and exercise control of a successor regime after Kim. This theory overlooks the fact that in Pyongyang's power structure, no military hardliner raises objections to Kim, once he has made a decision. They are all on the same boat, and they are determined to die together at the end if there is no way out.

Theory 5, the North sank the ship as a political and economic disruption to the South in reaction to the Seoul government's negative policy, suspending aid and limiting inter-Korea dialogue. The North also confiscated South Korean properties in the Mt. Geumgang tourist area. If this was its motivation, the attack already has had an impact on the party politics in Seoul. Yet it has had little impact on the South's rapid recovery from the global financial crisis. The North Koreans should understand that they are putting proponents of engagement into a politically shaky position. The Cheonan incident is already helping candidates of the conservative ruling party in the local elections slated for next month.

It is not easy to understand why the North would have sunk the South Korean ship when it had little to gain and much to lose. If the investigation exonerates North Korea in the end, it would be for lack of evidence. An acquittal would be advantageous for both Seoul and Pyongyang. What's your take?

Tong Kim is a research professor with the Ilmin Institute of International Relations at Korea University and an adjunct professor at Johns Hopkins University's School of Advanced International Studies (SAIS). He can be reached at tong.kim8@yahoo.com.