GUANTANAMO BAY, Cuba, July 23 (UPI) -- A former FBI agent told a U.S. military tribunal in Guantanamo Wednesday a defendant was present when Osama bin Ladin was briefed after the Sept. 11 attacks.

Bin Ladin's alleged driver, Salim Ahmed Hamdan, is being portrayed by prosecutors as a trusted subordinate to the terrorist leader, while defense attorneys say he was just an employee, The Washington Post (NYSE:WPO) reported.

Hamdan was interrogated in Guantanamo by FBI Agent Ali Soufan, who has since left the bureau. Soufan testified Hamdan told him bin Laden was "happy" about the 2001 attacks because he did not expect so many people to die.

Nearly 3,000 people were killed when hijacked airplanes were flown into the World Trade Center towers in New York and the Pentagon.

Soufan said Hamdan told him he first met bin Laden about 1996 in Kandahar, Afghanistan, after being recruited by a close bin Laden associate, the Post reported.

Hamdan's is the first U.S. military commission trial since World War II. A Yemeni, he was captured during the invasion of Afghanistan.