Technically the first one is still going on. North and South have always been in a state of war since 1950...it's just a matter of when they'll start shooting at each other full-time again.I'd love to see a united Korea within my lifetime (preferrably under the South's rule, of course), but unfortunately it seems like a lot of destruction will have to happen beforehand.
It's seems reasonable to believe that loss of support from PRC would be the main contributor.Unification is going to be a huge mess on the social/economic level. West/East Germany didn't have such a large disparity in income, quality of life, etc, and it's still not all roses and sunshine there 20 years later. Hopefully when it happens, they can apply some lessons learned.
cute North Korean soldier:http://picroda.jphip.com/korean/jphip03601.jpg