He uses it to justify, or is he simply pointint out a result of the invasion?
He uses it to deflect criticism of the fact that the Afghan mission is only a partial success rather than a total success. The purpose of the Afghan war was not just to overthrow the Taliban but to get Al Quaeda and Bin Laden. That goal has not yet been accomplished. The level of terrorist resistance to the U.S. in Afghanistan may not be as bad as Iraq but its not something to be complacent about either.