Intelligence is never black and white, human judgement is always needed to look for patterns, assess credibility, and determine how to responde to every “threat”. So in addition to this poll being nothing more than a survey of people’s trust in gov’t, I think it’s nearly certain that our intelligence community detected some signs that an attack was possible. Clearly they either missed or determined that whatever was known did not rise to the level of action that could have prevented 9/11. But I can’t fault them for that - the same thing probably happens every day.
weren’t there a number of Saudi nationals taking flight training in the U.S.?