North Korean Dam Issues

Apparently, North Korea has built several dams near the DMZ, and yesterday an unannounced discharge from one of them swept into South Korea and now six South Koreans are missing. Some are accusing the North Koreans of using the dams as a weapon against the South, and it may be the first setback in the recent thaw.

I'm not sure how likely it is that the North Koreans would have intentionally used the discharge against the South Koreans. It would not shock me in the least if the dams were built where they are as a possible weapon for a later time, but at the same time, incompetence seems to be a common problem with all such projects within North Korea. It is known for certain that one North Korean child also died in the incident, as his body was found yesterday in South Korea.

At the same time, this could be a security threat that is even harder to defend against than the traditiona one. Does South Korea have the right to invade or else blow up the dams that are causing these problems, if repeated discharges cause more deaths? It seems kind of ridiculous, but I can't think of anything else South Korea could do about it, short of just taking out the North Korean regime (and all the hell that would come with THAT).

I'm open to ideas. Oh, and for those who want to see where the river that flooded was, it's the Imjin River:

I think this again shows how horrible it is that Seoul is so close to the border. Again, I have no recommendations, but it's very worrisome for South Korea.