The impression I get, from talking to one Korean expat, is that the majority of S. Koreans blame Bush for dragging them into the conflict in Afghanistan and that plans were afoot to withdraw all their troops. Can anyone comment on whether this is accurate?
First, tell you friend to go figure out how to guard his country's northern border. I want all our U.S. troops there to come home now!
To your question, it may be accurate but it is anedotal. In other words, whoever you talked to may believe that but it is not representative of all thinking on the subject.
South Korea owes its existence to the U.S. Even if the U.S. is wrong in the Afghanistan conflict, Korea owes the U.S. its support. Not because the U.S. expects its but because it is the right thing to do.
Your friend sounds very young and irresponsible. Or perhaps he figures no matter what he does the U.S. will always come to the aid of his country.
He may be correct in that view - unless one day the U.S. is prevented from coming to anyone's aid because, say, a nuclear tipped warhead capable of reach the U.S. prevents it from doing so.