reason that we should have stayed, why we did stay after overthrowing taliban. you're quite correct. a lot of other missions got added on. i think that was clearly a mistake. but it still made sense and would make sense to stay there now as an insurance policy to make sure that groups like al qaeda, isis and others can't take root there, can't get sanctuaries in afghanistan to threaten us in the united states and threaten our allies around the world. >> biden yesterday in his statement pointed the finger, in part, at the afghan military for folding here, which is not an unfair criticism. i wonder where you place the blame, and why you believe the afghan military, supported for 20 years both by american blood and treasure and training and advise and support, why the military didn't stand up to the taliban. >> well, i think this was part of the misconception about what our role was in terms of the nation building project. i think there was a lot of