People have long memories; especially in Korea's case. America was, and is, perceived as an Imperialist aggressor. America's invasion of North Korea and the subsequent defeat of hers and Allied forces by the Red Army of China which came to the aid of the Koreans is still remembered.
America tried to fight an idealogical war and failed dismally. The same happened in Vietnam and the same thing is happening in the Middle East.
Isn't it about time America got the idea that losing wars isn't a great idea?