Since Osama bin Laden and his followers were driven from their bases in Afghanistan, the Al Qaeda terrorist network has demonstrated an increasing ability to exploit the Internet as it reconfigures itself as a semi-leaderless global extremist movement far more elusive than the original incarnation.
Websites run by Al Qaeda and its backers have become virtual classrooms for terrorists, offering instructions for activities such as kidnapping and using cellphones to set off bombs, like the ones used in Madrid. Independent Al Qaeda cells and the network's loose hierarchy use easily available encoding programs and simple techniques to exchange virtually undetectable messages between Internet cafes in Karachi and libraries in London.
The Internet's importance to Al Qaeda was highlighted this month by the disclosure that Pakistani authorities had apprehended Mohammed Naeem Noor Khan, a suspected Al Qaeda computer engineer, and collected a wealth of electronic material.
E-mail and other information from Khan's computers led to the arrests of 13 suspects in Britain and sent investigators scrambling to unravel electronic links among militants in Pakistan, Europe and the United States, British, U.S., and Pakistani authorities said. The discovery of files on financial institutions in New York and Washington among Khan's trove also played a role in prompting the Bush administration to issue a terrorist warning.
Although it has long been known that Al Qaeda used the Internet to conduct reconnaissance on potential U.S. targets, the disks and hard drives taken from Khan disclose much about the resiliency and adaptability of a far-flung network hiding in plain sight, said U.S. and foreign intelligence officials and outside experts interviewed for this report.
"The Internet allows the organization to become a virtual self-perpetuating and changing entity in cyberspace that provides technological guidance and moral inspiration to a new generation," said Magnus Ranstorp, a counter-terrorism expert at the University of St. Andrews in Scotland.
Note also, later in the article, the keen political analysis from the jihadists:
But the posting that called for attacks on U.S. allies in Iraq — and its chilling effectiveness — has proved the most startling.
"It shows that they are very strategic in what they are doing," the U.S. national security official said.
The document was posted on a website run out of the Middle East. Its language, religious references and other telltale signs convinced U.S. experts that an Al Qaeda member wrote it, though they have not identified the author.
Titled "Jihad in Iraq: Hopes and Dangers," the posting advocated attacking countries aligned with the U.S. that were most vulnerable to pressure to withdraw their troops from Iraq. Italy and Spain were singled out, with a special mention of Spain's approaching elections.
"Withdrawal of Spanish or Italian forces would put immense pressure on the British presence in a way that Tony Blair (news - web sites) might not be able to bear," it said in one of several paragraphs underlined for emphasis. "In this way the dominoes will begin to fall quickly."
At another point, the posting said, "We think that the Spanish government could not tolerate more than two, maximum three blows, after which it will have to withdraw as a result of popular pressure."
The posting was available on one of the hundreds of Arabic-language websites that cater to extremists and moderates alike. Many of them are watched by intelligence and law enforcement agencies, but experts say there are far too many to monitor thoroughly.
Evan Kohlmann, a Washington-based terrorism analyst who has been a consultant to the U.S. government, said he was monitoring an Internet chat room frequented by Islamic extremists last month when someone posted copies of the complete Windows desktop of a U.S. soldier serving in South Korea.
The soldier had apparently installed a program to access his work computer through another computer and the hacker found a back door and took control of the machine by using simple techniques, Kohlmann said.
Simplicity seems to work best. One common method of communicating over the Internet is essentially an e-mail version of the classic dead drop.
Members of a cell are all given the same prearranged username and password for an e-mail account on an Internet service provider, or ISP, such as Hotmail or Yahoo, according to the recent joint report by the Treasury and Justice departments.
One member writes a message, but instead of sending it, he puts it in the "draft" file and then logs off. Someone else can then sign onto the account using the same username and password, read the draft and then delete it.
"Because the draft was never sent, the ISP does not retain a copy of it and there is no record of it traversing the Internet — it never went anywhere, its recipients came to it," the report said.
Secure messages also can be transmitted using widely available encryption tools.
Slightly more advanced methods allow messages to be embedded in image, sound or other files transferred over the Internet through a process called "steganography." The files cannot be distinguished without a decoding tool.
The difficulty of intercepting and deciphering messages has given rise to a game of cyber cat and mouse, according to government and independent experts.
In an effort to gather information on potential recruits and donors, U.S. law enforcement agencies operate websites that are set up to resemble extremist Islamic sites. Visitors leave an electronic trail when they enter the site.
On the other side, Al Qaeda can transmit false information to determine whether its members are being monitored by law enforcement.
The Internet offers stealth to its users, but authorities can get valuable information if they can get their hands on data stored in computers or on disks.
U.S. and foreign investigators still are sifting through the material taken from Khan. By cross-referencing the data with old files on people, places and methods of attacks, they hope to get a new picture of the organization's operations and identify its operatives, senior U.S. law enforcement officials say.
They also are getting a closer look at the role of the Internet in Al Qaeda's strategies — and a rare chance to turn the tables on the organization's computer prowess.
"Al Qaeda relies on the Internet just like everyone else, and increasingly more so," a senior Justice Department official said. "But that reliance could also come back to bite them."