South Korea may be/ may have worked on Nukes as well.

I found this on CNN.com: http://www.cnn.com/2004/WORLD/asiapcf/09/02/skorea.nukes/index.html
It looks as if S. Korea may have had a bit of a nuclear program themselves. It hasn't been really decided if it was accidental or intentional. Regardless, this will probably change the political atmosphere in the region very quickly.