Four of the five main online forums that al-Qaida's media wing uses to distribute statements by Osama bin Laden and other extremists have been disabled since mid September, monitors of the Web sites say.
The disappearance of the forums on Sept. 10 - and al-Qaida's apparent inability to restore them or create alternate online venues, as it has before - has curbed the organization's dissemination of the words and images of its fugitive leaders.
For al-Qaida, "these sites are the equivalent of pentagon.mil, whitehouse.gov, att.com," said Evan Kohlmann, an expert on online al-Qaida operations who has advised the FBI and others. With just one authorized site still in business, "this has left al-Qaida's propaganda strategy hanging by a very narrow thread."
On several occasions over the past three years, unknown hackers have shut down al-Qaida-affiliated Web sites after they announced the imminent release of a new video message from bin Laden or another extremist leader. It is often impossible to pinpoint the source of such online attacks, though some experts say the culprits could be independent activists.