Al-Awlaki has also been linked with some of the hijackers involved in the attacks on Sept. 11, 2001. He was said to be the spiritual advisor to two of hijackers and may have met with them before the 9-11 attacks – and known about them ahead of time. Some of his sermons were attended by the hijackers the same year of the attacks, and the phone number of his mosque was found in an apartment in Germany belonging to one of the 9/11 plotters.