A growing consensus of counterterrorism analysts who track Al Qaeda’s use of social media say terrorist groups are embracing Twitter and Facebook in an effort to gain support.

Although there is anecdotal evidence of social media’s role in recruiting, there are few empirical studies.

“Baseline quantitative research barely exists at the moment,” terrorism analyst Will McCants told a U.S. House security subcommittee in December 2011. “Analysts are either focused on studying the content of the propaganda or absorbed in stopping the next attack by known militants.”

But a new report from the New America Foundation comparing the popularity of English and Arabic jihadi forums over a three-month period found that more individuals and organizations have been using Twitter feeds to “promote their activities.”

The study’s author, analyst Aaron Zelin, wrote that “this trend is likely to continue.” But he also found that Twitter is unlikely to replace the group’s use of web forums that better allow for private communications and “the sense of authenticity and exclusivity.”

Arabic sites also greatly outnumbered English-language forums, he found.

Somalia-based Al Shabab has been the most prolific since joining Twitter in late 2011,often posting battle reports and photos of the dead on its Twitter account with the hashtag #JihadDispatches. Twitter shut down the account in January after the Shabab threatened to kill hostages, but 10 days later there was a new account under a different name.

The Shabab has had a slick, articulate English-language public relations team for years. An email from the “Press Office,” signed “Regards,” recently informed journalists that the group’s email address had changed.

The organization’s most famous foreign member, Alabama native Omar Hammami, has used his Twitter account both to spread his ideology and to report threats on his life. Hammami, who spent a brief period living in Toronto and goes by the name Abu Mansoor Al-Amriki (the American), split with the group’s Somali hardline members and is reportedly in hiding. Some believe he went public to help spare his life by exposing the threat.

Although the use of Twitter, YouTube and, to a lesser degree, Facebook is a new phenomenon, extremists have always used web forums and chat groups to spread propaganda and try to recruit foreign members, often referred to as “homegrown terrorists.”

“All of these online outlets provide a way for those who are passively interested to contact people who are actively interested,” says J.M. Berger, author of Jihad Joe and an extremism researcher. “What happens is they get involved and talk to people and if (the administrator) thinks you’re sincere, they will steer you toward someone else in a closed forum.”

Zelin recommended in his report that rather than attempt to permanently shut down the sites and accounts, the intelligence community should mine the data for information and only disrupt operations occasionally.

This debate on whether to collect intelligence or take jihadi sites offline has gone on for years, says Thomas Hegghammer, a fellow at Stanford University and researcher with the Norwegian Defence Research Establishment.

“The de facto consensus has been to leave them and disrupt a little, instead of trying to close everything down,” he said. “The thing that complicates it is that I think the capabilities of the services have increased . . . I think it now is possible to close and keep closed most of the forums. You can close down the hubs and meeting places.”

As for Twitter, where jihadists have turned when intelligence agencies have shut down forums temporarily, Hegghammer does not think the groups have generated enough of a following to be of serious concern yet.

“The Twitter account of the Ansar al Mujahideen Forum got 400 followers in a matter of months. That’s tiny,” he noted. “When I went on Twitter a couple of months ago, I had about the same after one day.”