Since the South Korean warship Cheonan sank off the coast of the Korean Peninsula on March 26, stakeholders in Northeast Asia have worked hard to defend their interests.

On May 20, South Korea announced the sinking was caused by a torpedo launched by North Korea. On July 9, the UN Security Council condemned the attack without identifying the attacker. In response, South Korea and the U.S. announced a plan to hold a joint naval exercise in the Yellow Sea, which led to strong opposition from China.

The sinking of the Cheonan was a great loss to South Korea. It's understandable that Seoul wanted an investigation. However, due to its direct connection with the case, any unilateral conclusion made by South Korea lacked objectivity. Although the U.S., Australia, UK and Sweden joined the investigation, the findings are not objective, because the four are either allied with South Korea or allied with South Korea's allies. An objective investigation should involve countries not allied with South Korea, especially those with key interests in Northeast Asia, such as China and Russia.

Yet, just the opposite occurred. South Korea investigated for two months, and it's possible some evidence was altered, which would undermine the credibility of the findings. Although we can't say the investigation was biased, we can't be sure it's fully credible either.

Judging by the damage absorbed by the Cheonan, an outside attack is probable. But this doesn't prove the North Korea fired the torpedo. Both the U.S. and South Korea have such torpedoes. All three countries are able to launch such a strike. And theoretically, China could have launched such an attack as well.

The attack might have been deliberate, but an accidental or an unauthorized launch is possible as well. There's also a possibility that the Cheonan did something provocative that led to the attack.

If the attack did not emanate from South Korea, or U.S., then deterrent drills are justifiable. Actually, the two hold drills quite often to prepare for potential external threats or to present joint threats to other countries.

When the Cheonan sank and claimed 46 lives, China expressed its condolences to South Korea, but the goodwill gesture came much too late. This indicates that China needs to improve its diplomatic awareness and responses to crisis. Nonetheless, it's regrettable that South Korea didn't invite China into the initial investigation. If it had invited China to join the investigation, South Korea could have presented a more credible finding while displaying adept diplomatic skill in giving China a role.