The gist of their messages hasn't changed much. But the frequency of them has. Since Sept. 11, 2001, members of Al Qaeda have released an audio- or videotape about once every six weeks.
Most notably, Osama bin Laden, invisible to the world for more than two years, sent a videotape to Al Jazeera just three weeks ago. Before that, a young man claiming to be an American recorded a 75-minute screed on a videotape that was delivered to ABC News along the Afghanistan-Pakistan border.
But the communication is hardly limited to the airwaves. Abu Musab al-Zarqawi alone has posted messages on the Internet to his followers in Iraq several times in the past week, urging them to resist the US campaign in Fallujah.
The routine appearance of these tapes and Internet postings, despite tighter security, highlights Al Qaeda's growing sophistication in producing and airing messages for internal communication as well as for shaping global opinion.
They also show how, in an era of satellite television and the World Wide Web, it is nearly impossible to stop boutique terror groups - small homegrown cells that can reach mass audiences with just a videocamera and a few stylish graphics.
"If they can communicate [through] these tapes to us, and not worry about getting caught, they can communicate clandestinely to their followers," says Brian Jenkins, a terror expert at the RAND Corp. in Santa Monica, Calif. "This suggests there's a bit of machinery working here."
Military officials have thought it would be difficult for Al Qaeda leaders to coordinate operations because they couldn't use telephones, which are traceable. But marines in Fallujah this past week found computers that appear to indicate that Mr. aZarqawi and Al Qaeda leaders outside Iraq at least tried to talk with one another in cyberspace.
"I think there are attempted communications between Zarqawi and bin Laden," Lt. Gen. Lance Smith, deputy commanding general of the US Central Command said recently. "And whether it is to congratulate him on having announced that he wants to be part of Al Qaeda, or whether it's to communicate and give him instructions, or what it is, we don't know."
Still, it's the recruitment value of other tapes that has government officials and terror experts most concerned. Al Qaeda leadership videos are almost always played in their entirety to the Muslim world on Al Jazeera, the Qatar-based 24-hour news channel.
Small segments of them are normally shown in the US. And the transcripts are almost always posted on the Internet.
The tape that was delivered to ABC News nearly a month ago, by a man calling himself Azzam the American, still baffles intelligence community officials here.
The FBI posted a four-minute segment of the tape and a partial transcript, along with an "urgent" request for help in identifying the individual, on its website on Oct. 30, the day after ABC aired a similar segment.
According to an FBI spokesman, the bureau has received several tips but still hasn't identified the man definitively. Yet some intelligence officials believe he is Adam Gadahn, a young man who converted to Islam and left California for Pakistan six years ago.
That tape is a 75-minute diatribe echoing bin Laden's claims that Islam is under attack by the West - occupying lands and exporting corrupt values. It says that continuous jihad is the only solution.
Like bin Laden's message that followed it, where he appeared to sit statesmanlike in a broadcast studio and lecture Americans, Azzam's message was aimed at the US public.
This is a new development, Jenkins says. Al Qaeda is expanding its recruitment efforts beyond the traditional Arab and Muslim world, reaching out to people who can more easily move among the cities of Western Europe or North America.
"It's a recruiting pitch," says Jenkins, who has spent much of the past year trying to look at the world from Al Qaeda's viewpoint and who evaluated a transcript of this 75-minute interview obtained by the Monitor.
"For them, recruiting is much closer to missionary work.... Above all, the purpose of this screed is to enlist people in the greater cause of jihad."
Circulation of the message is the key to its success, say Jenkins and other intelligence officials. Bin Laden's messages, for example, are almost always aired in their entirety in the Muslim world, although only 15- to 30-second sound bites are broadcast in the US. Only a few minutes of the Azzam tape were aired in the first ABC broadcast, and most newspapers carried only a few of Azzam's quotes.
But the FBI may be unwittingly helping Azzam spread his message by its online posting. "The FBI's helping him out here, more than ABC actually," Jenkins says.
But the overarching message from the tape is that Al Qaeda's communications systems are evolving to outwit security measures imposed by governments and are succeeding as a recruiting tool.
"Their communications systems are light-years more sophisticated than they were on 9/11," says Michael Scheuer, a former senior intelligence official who studied Al Qaeda for more than a decade. "Not only is it sophisticated, but prompt and the quality is high. They pretty much dominate the Internet in terms of Islamic literature. - it's of very high quality, controversial, interesting to read, and appeals to Muslims."