>> i will leave to others how they might want to label those activities. >> reporter: brennan's explanation, the cia was not ready after 9/11. >> the program was uncharted territory for the cia, and we were not prepared. >> reporter: and he maintained the agency's enhanced interrogation techniques, or eits, produced intelligence, even though he conceded it was unknowable if the same results were attainable without harsh methods. >> it is our considered view that the detainees who were subjected to enhanced interrogation techniques provided information that was useful and was used in the ultimate operation to go against bin laden. >> reporter: that's in sharp contrast to the torture report from democratic senate intelligence committee chair dianne feinstein. she responded to brennan in a tweet that critical intelligence that led to bin laden was unrelated to eits. but former cia officials insist they were doing what was