How was the Korean War both a success and a failure for American forces?

It was a success because the mission was accomplished; the communists were stopped; and the Republic of South Korea was preserved. It was never a failure.

THAT IS NOT TRUE! Gosh people... North Korea is STILL COMMUNISM, and if you need to know if FOR the US it was a success then DON'T ask! NO offense but there are SO MANY ignorant people that DON'T know what to say! NORTH KOREA IS STILL COMMUNIST and IT WAS COMMUNIST ALSO 62 YEARS AGO!