In my opinion, South Korea is our most unreliable ally. Just this week, in the wake of North Korea's [failed] nuclear test and the US' push for UN sanctions, Seoul announced that they would not cooperate and temporarily sever economic ties.
Franky, South Korea's behavior vis-a-vis Pyongyang is positively schizophrenic. In the 1950s, the US and the UN saved South Korea from a Chinese-backed invasion by the north. Now they act as if the North is not a threat to them. And yet they don't seem to mind having American troops risking their lives to protect their country from - wait for it - the North Koreans.
So, why are the South Koreans fighting us so as to maintain economic ties that prop up the most brutal and sadistic regime on the face of the earth?