Bin Laden son-in-law unexpectedly testifies
Abu Ghaith, 48, is one of the highest profile people with purported links to al-Qaeda to be tried in a US civilian court, Reuters news agency reported.
Prosecutors in federal court in New York have accused him of serving as a spokesman and recruiter for al-Qaeda and of knowing about planned attacks against Americans, accusations he denied on Wednesday.
Abu Ghaith's decision to testify came a day after US District Judge Lewis Kaplan ruled that jurors would not hear testimony from Khalid Sheikh Mohammed, the accused mastermind of the September 11 attacks.
Mohammed is being held at the US military prison in Guantanamo Bay, Cuba.
Abu Ghaith said on Wednesday that he met Mohammed while in Afghanistan but that they did not discuss any planned attacks.
Under questioning from his lawyer, Stanley Cohen, Abu Ghaith on Wednesday described meeting Osama bin Laden, a founder of al-Qaeda, in Afghanistan just hours after the hijacked plane attacks of September 11, 2001, which killed about 3,000 people.
After driving several hours into the mountains, Abu Ghaith said that he had met bin Laden and several of his lieutenants,
including Ayman al-Zawahiri, the Egyptian now considered al-Qaeda's leader, inside a cave.
Bin Laden was killed in May 2011 by US forces at his hideout in Pakistan.
Abu Ghaith testified that bin Laden asked him if he had heard about the attacks but he said he first learned about the attacks from news reports.
"We are the ones who did it," bin Laden said, according to Abu Ghaith. "What do you expect to happen?"
Oppression of Muslims
Abu Ghaith, who was speaking through an interpreter, said he predicted that the United States would not rest until it had accomplished two things: killing bin Laden, and toppling the Taliban government in Afghanistan.
"He said, 'You are being too pessimistic'" Abu Ghaith told jurors.
He acknowledged making several videos at bin Laden's request, including one in which he warned that a "storm of airplanes" was coming, but denied that he had any advance knowledge of other plots, such as the shoe bomb that Briton Richard Reid attempted to detonate aboard an airplane in 2002.
Instead, he said, bin Laden asked him to deliver a "message to the world" in his role as a speaker and an Imam.
His speeches were based on talking points that bin Laden gave him, he said.
He also claimed that some videos were an attempt to counter the propaganda against Muslims from the United States.
"My intention was not to recruit anyone," he said. "My intention was to deliver a message, a message I believed in, that oppression, if it befalls any nation, any people, any category of people, that category must revolt.
"What happened was a natural result of the oppression that befell Muslims."
Abu Ghaith also said he had never became a member of al-Qaeda.