According to the indictment unveiled Thursday, Abu Ghaith was engaged in planning and perpetrating a federal crime of terrorism against the United States and its citizens. He could face a life sentence if convicted.

In May 2001, Abu Ghaith urged individuals at a guest house in Kandahar, Afghanistan, to swear allegiance to bin Laden, according to the charges. A day after 9/11, the alleged spokesman warned the United States and its allies that a "great army is gathering against you" and called on "the nation of Islam" to battle "Jews, the Christians and Americans," the indictment states.

Abu Ghaith later warned "the storms shall not stop, especially, the airplane storms" and warned Muslims and foes of the United States not to board aircraft or live in high-rise buildings, according to the indictment.