For several months after the 9/11 attacks, no one, nor any group, claimed responsibility for the attacks, so the primary responsibility fell solely upon the hijackers, all of whom were killed and all of whom left no message or any claim of responsibility, explaining why they had carried out the attacks. read more
In December 2001, the Pentagon released a videotape in which bin Laden is shown at a dinner with associates in Afghanistan on Nov. 9, 2001, saying the destruction of the Sept. 11 attacks exceeded even his "optimistic" calculations. read more