The US had no real choice about going into Afghanistan in 2001. The Taleban were harbouring the terrorists who caused 9/11 and were refusing to give them up. In the main, the original campaign using the Northern Alliance was an effective way of delivering the desired result - removal of the Taleban.
The mistake was then trying to 'nation build'. The right move would have been to immediately walk away and leave the country to sort itself out (or not).
Last edited by Red Line Entry; 25th Sep 2012 at 10:30.