You do know that article is about Iraq years ago and not Afghanistan?  AF isn't even mentioned in it.  But here is the bottom line as to why we are in AF in my opinion, to prevent it from becoming a safe haven for terrorist groups to plan terrorism, train terrorists, r&r terrorists, and fund terrorism, AGAIN.  Now if you feel those reasons are invalid and we should just leave, that's your prerogative and vote for those who agree with you.  Unfortunately for your view, very few people who study and are paid to deal with national and global security concerns agree with that view.  Myself, I think the threat and concerns are real and worth keeping an appropriate level of hard and soft power in AF for the foreseeable future.  The question we should be addressing is (in my opinion), what is the appropriate level?