Though U.S. officials have no evidence that the younger bin Laden played a role in the Sept. 11 attacks on the World Trade Center and Pentagon, Saad bin Laden has provided financial and other logistical support for several al Qaeda operations, said one official, speaking on the condition of anonymity.
Saad, a Saudi like his father, is thought to be in his early 20s, and is one of Osama bin Laden's eldest sons, officials said. Also, like his father, he is thought to currently be in the Afghanistan-Pakistan region.
Osama bin Laden, himself in his mid-to-late-40s, has at least 23 children by numerous wives, officials said.
"Some of them share his ideology," one counterterrorism official said. "(Saad) is definitely a believer."
Saad bin Laden is believed to have provided support for al Qaeda's April 11 bombing of a synagogue in Tunisia that left 19 dead, most of them German tourists. This marked al Qaeda's first successful terrorist operation outside of the Afghanistan region since the Sept. 11 attacks.
Al Qaeda leader Khalid Shaikh Mohammed, the suspected mastermind of the Sept. 11 attacks, is believed to be a close associate of Saad bin Laden. Mohammed — who is thought to outrank Saad bin Laden in al Qaeda's pecking order — has also been linked to the Tunisia bombing, U.S. officials have said.
Officials attributed Saad's importance to simple blood ties: when most of the world is hunting for him, Osama bin Laden can trust his son.
He began his rise last year as the United States went to war on al Qaeda in Afghanistan and elsewhere, officials said.
His position has accelerated even as the terrorist network decentralized its power structure. This move, under way since earlier this year, gives commanders in the field more authority to conduct terrorist operations without guidance from bin Laden's inner circle.
However, officials have no clear evidence that Saad bin Laden is positioned to take over al Qaeda in the event of his father's death or capture.