It was some hours after the World Trade Center towers had been toppled when Sulaiman Abu Ghaith was summoned to a meeting with Osama bin Laden. He recalled a three-hour-or-so drive into the night, finding the leader of Al Qaeda in a cave amid the mountains in Afghanistan.

Bin Laden wanted his opinion on what would happen next, Mr. Abu Ghaith testified on Wednesday. He said he told Bin Laden that he was not a military analyst, but Bin Laden pressed him, The New York Times reported.  

Mr. Abu Ghaith said he told him that “America, if it was proven that you were the one who did this, will not settle until it accomplishes two things: to kill you and topple the state of Taliban.

“He said, ‘You are being too pessimistic.’
“I said, ‘You asked my opinion, and this is my opinion.’ ”

In the weeks after the Sept. 11 attacks, Mr. Abu Ghaith, who later became Bin Laden’s son-in-law, served as a spokesman for him, amplifying some of his pronouncements, and giving voice, prosecutors say, to a broad recruitment drive for fighters committed to wage war on the United States.

On Wednesday, Mr. Abu Ghaith gave voice to his own cause, unexpectedly taking the stand in a federal courtroom in Manhattan to defend himself against charges that include conspiring to kill Americans and providing material support to terrorists. He is the most senior Bin Laden adviser to be tried — let alone testify — in a civilian trial in the United States since the attacks, and he offered an extraordinarily intimate look at Bin Laden at the time, taking jurors inside his cave in Afghanistan.

After the drive from Kandahar, Mr. Abu Ghaith said, he found Bin Laden “in a cave, inside a mountain, in a rough terrain.”

“He said, ‘Come in, sit down.’ He said, ‘Did you learn about what happened?’ ”

Bin Laden told him that “we are the ones who did it,” the defendant recalled in response to questions posed by his lawyer, Stanley L. Cohen.

The decision by Mr. Abu Ghaith, a 48-year-old Kuwaiti-born cleric, to testify came two weeks into his trial in Federal District Court. Late on Wednesday, the defense rested its case. The jury is expected to begin deliberations early next week.

Mr. Abu Ghaith had been in Afghanistan for several months in 2001, where he was delivering religious lectures in Qaeda training camps, he said. On the morning of Sept. 12, he testified, Bin Laden told him he wanted “to deliver a message to the world.”

Mr. Abu Ghaith recalled saying that he was “new in this field.” He said Bin Laden replied, “I am going to give you some points and you build around them that speech.”

In those videotaped speeches, the first delivered on Sept. 12, 2001, as he sat beside Bin Laden, Mr. Abu Ghaith praised the Sept. 11 attacks and warned of others to come.

Mr. Abu Ghaith’s decision to testify gave federal prosecutors a rare chance to cross-examine someone who was so close to Bin Laden, and the government took full advantage of the opportunity.

Mr. Abu Ghaith had said under direct examination, for example, that Bin Laden wanted him to lecture in the Qaeda camps because the trainees had a “hard life.”
“I need you to change that,” Bin Laden told him, Mr. Abu Ghaith recalled. He said Bin Laden wanted him to make them be merciful.

Seizing on that moment, a prosecutor, Michael Ferrara, later asked Mr. Abu Ghaith, “You’re telling this jury that Bin Laden asked you to speak at those training camps where men were armed and learning how to use guns because he wanted you to talk about mercy?”
“Yes,” Mr. Abu Ghaith replied.

Mr. Abu Ghaith had also testified on direct examination that he had no idea “specifically” that the Sept. 11 attacks would occur, saying he only learned of them from news reports.

But on cross-examination, he admitted that in the training camps, he had heard that “something” might happen.
“You knew something big was coming from Al Qaeda?” Mr. Ferrara asked.
“Yes,” Mr. Abu Ghaith replied. "He had hoped that his speeches and videos would have led the United States to say, 'Let’s go and sit down and talk and solve this problem…

Until Mr. Abu Ghaith took the stand, his lawyers had given no indication that they were going to have their client testify. The defense’s strategy had been to obtain the testimony of Khalid Shaikh Mohammed, the self-described architect of the Sept. 11 attacks; the defense had argued that testimony from Mr. Mohammed, given his vast knowledge of Al Qaeda’s operations, would help clear their client.

But the judge, Lewis A. Kaplan, would not allow Mr. Mohammed’s testimony, ruling on Tuesday that there had been no showing by the defense, with rare exceptions, that Mr. Mohammed “has personal knowledge of anything important to this matter.”

Asked by Mr. Cohen whether he had ever taken part in any plan to kill Americans or anyone else, Mr. Abu Ghaith said no. He also said he had met Mr. Mohammed but only engaged in “casual talk” with him. He denied that he and Mr. Mohammed had ever discussed terrorist plots.

Prosecutors have not accused Mr. Abu Ghaith of helping to plan or carry out the Sept. 11 attacks. But prosecutors have said that Mr. Abu Ghaith knew of the Qaeda plot in which Richard C. Reid tried to blow up a trans-Atlantic airplane with explosives in his shoes — an assertion he denied on Wednesday.

The government has said in court papers that as part of his role in the conspiracy and the support he provided to Al Qaeda, Mr. Abu Ghaith spoke on behalf of the terrorist group, “embraced its war against America,” and sought to recruit others to join in that conspiracy.

Mr. Abu Ghaith responded calmly as he was questioned; at one point, as the government played a video of one of his fiery speeches, he rested his head on his hand and appeared to be impassively watching a monitor on the witness stand.

During the questioning by Mr. Cohen, Mr. Abu Ghaith said that he had hoped that his speeches and videos would have led the United States to say, “Let’s go and sit down and talk and solve this problem.”

Mr. Ferrara, though, pressed the defendant about the message he delivered in his speeches.
“It was your intention to deliver a message you believed in, right?” the prosecutor asked.
Mr. Abu Ghaith said yes.

“Your words carried weight, didn’t they?” Mr. Ferrara added a few questions later.
“The listener will have to be the judge of that,” Mr. Abu Ghaith said. “I cannot judge my own words.”

BBN/SSR/AD-20Mar14-11:09 am (BST)