I actually has no problem with united Korea. Koreans are more nationalistic than people give them credits. Unlike Japan, S Korea isn't a loser in WW2. The only reason the US can justify their existence in S Korea is N Korea. Without N Korea, the US will have difficulty to justify its military base in S Korea. More importantly, there will be a lot of economic activities in the northern part and China can take part in it. My main problem with N Korea is that the Kim dynasty is extremely stupid in economics.