Clinton knew about the attack the planning started on his watch. Plus, his B.J. Was leaked intentionally to keep the MSM off the espionage trail where Politicians from the top down and military brass were selling classified information to China. This is TREASON but, not for the to big to jail above the law corrupt politicians. There is so much corruption and nobody seems to know anything. MSM covers it up nicely.
Although it seems unfair to attach a terrorist attack to a sitting president, but there is evidence to suggest that there were several steps that could have been taken in order to stop the attack of 9/11. There were systemic failures that caused fail safes in our security system to not operate properly, which can be attributed to leadership.
While conspiracy theorists believe preparation for the 9/11 attacks is apparent on numerous occasions throughout American federal documents, Clinton has in no way (in my experience) expressed any responsibility for what happened. Since the attack took place while Bush was in administration, he has taken almost the full brunt of the blame, and even passed some along to his successor.