This is a tough question and I don’t think there’s a perfect answer. So far I’ve figured that it would be very destabalizing to leave right now therefore not worth it. It’s a hard line to walk because if the occupation* goes on indeinitely that obviously is bad as well.
I read an interesting article today called What’s wrong with cutting and running? written by the former head of the NSA under Reagan. While I don’t think I agree with the eventual conclusion, all of his points are totally valid. I like seeing a real discussion of the question “Would things actually be worse if they left?” He takes all of the potential problems being cited for not pulling out and examines each in detail. Good read.
*I’m sure someone will comment that “it’s not an occupation because the government hasn’t kicked them out.” It’s still an occupation while the following are true: a) the majority of the population doesn’t want them there, b) the US forces are holding the population under martial law, and c) the US forces are free to do whatever they want. Go look up the definition of the word.