WASHINGTON — Al Qaeda fighters have been using secretive chat rooms and encrypted Internet message boards to plan and coordinate attacks — including the threatened plot that US officials say prompted the closing of 19 diplomatic posts across Africa and the Middle East for more than a week.
It’s highly unlikely that Al Qaeda’s top leader, Ayman al-Zawahri, or his chief lieutenant in Yemen, Nasser al-Wahishi, were part of the Internet chatter or, given the intense manhunt for both by US spy agencies, that they ever go online or pick up the phone, experts say.
But the unspecified call to arms by the Al Qaeda leaders, using a multilayered subterfuge to pass messages, provoked a quick reaction by the United States to protect Americans in far-flung corners of the world where the terror network is evolving into regional hubs.
For years, extremists have used online forums to share information and drum up support, and over the past decade they have developed systems that blend encryption programs with anonymity software. Jihadist technology may now be so sophisticated, experts say, that many communications avoid detection by National Security Agency programs.
A US intelligence official said the unspecified threat was discussed in an online forum joined by so many jihadist groups that it included a representative from Boko Haram, the Nigerian insurgency that has informal ties to Al Qaeda.
Two other intelligence officials characterized the threat as more of an alert to get ready to launch potential attacks than a discussion of specific targets.
One of the officials said the threat began with a message from Wahishi, head of Yemen-based Al Qaeda in the Arabian Peninsula, to Zawahri, who replaced Osama bin Laden as the core Al Qaeda leader. The message essentially sought Zawahri’s blessing to launch attacks. Zawahri, in turn, sent out a response that was shared on the secretive online jihadi forum.
All three officials spoke on condition of anonymity.
Zawahri was last believed to be in Pakistan, and Wahishi is said to be in Yemen. Given the nearly 2,000 miles between the two men, it’s most likely they separately composed encrypted messages, saved them on thumb drives, and handed them to couriers who disseminated them on secure websites, said Rita Katz, director of SITE Intelligence Group.
‘‘These guys are not living in a bubble,’’ said Katz. ‘‘They live in a reality that is facing the American intelligence interception with the best, most advanced technology that can be created. So they always try to find ways to get away from these interceptions to be able to deliver messages.’’