Since September 11, 2001, the organization responsible for the terrorist attacks, al-Qaeda, has greatly changed. Experts like Georgetown University's Bruce Hoffman noted al-Qaeda's transformation from what was once a hierarchical organization with a large operating budget into an an ideological movement, saying the group had simply “gone back to its roots.” Whereas al-Qaeda once trained its own operatives and deployed them to carry out attacks, today al-Qaeda is just as likely to inspire individuals or small groups to carry out attacks, often with no operational support from the larger organization. More recently, Hoffman and others have noted a resurgence (LAT) in al-Qaeda's operational capacity. A July 17, 2007, National Intelligence Estimate, says that al-Qaeda remains a threat to the United States and has regained its strength, particularly in the tribal areas of Pakistan.

Prior to 2001, al-Qaeda enjoyed the support of Afghanistan's Taliban government, which provided both financial assistance and a safe haven in which to operate terrorist training camps. According to the 9/11 Commission Report, the group had an annual operating budget of $30 million and from 1996 to 2001, 10,000 to 20,000 fighters underwent training in al-Qaeda's Afghan camps.

Under these conditions, al-Qaeda planned and carried out the 9/11 attacks as well as the 1998 bombings of U.S. embassies in Kenya and Tanzania, the 2000 bombing of the destroyer USS Cole in Yemen, and the simultaneous 2002 attacks on a Mombasa hotel and an Israeli passenger jet. At the same time, al-Qaeda funneled money and fighters to conflicts in such places as Chechnya, the Balkans, Tajikistan, and Kashmir. According to a 2001 U.S. State Department report, as al-Qaeda grew in profile, it became an "umbrella organization for a worldwide network [of] Sunni Islamic extremist groups."

The international crackdown that followed the 9/11 attacks greatly cut into al-Qaeda's resources. Many of al-Qaeda's former leaders have been captured or killed. When the U.S.-led coalition invaded Afghanistan, al-Qaeda no longer enjoyed the ability to operate freely there. The elements of al-Qaeda that persist in Afghanistan today are a shadow of the former operation: No major training camps operate, no government supports the organization, and the constant threat of attack from coalition forces looms. Al-Qaeda has lost much of its financial muscle, too. In the last five years, the U.S. government claims some $140 million in terrorist funds have been seized worldwide, much of which have come from al-Qaeda.

While the group's aims—uniting Muslims to overthrow "un-Islamic" regimes and expelling Westerners from Muslim countries—remain, it has adjusted the ways in which it pursues them. Most important has been a shift in structure from an organization that plans and carries out terrorist attacks to a more nebulous, loosely affiliated network aiming to incite acts of terrorism. As Fawaz Gerges, a professor of Middle Eastern studies at Sarah Lawrence College, explains, "Al-Qaeda central no longer exists." He says al-Qaeda's senior leaders like Osama bin Laden and Ayman al- Zawahiri "are more preachers of global jihad than field lieutenants who give direct orders."

Some experts suggest the group has always viewed itself as an ideological movement, which spawned an operational hub in Afghanistan. "Basically there are two al-Qaedas," says Jason Burke, a terrorism expert and reporter for the Observer. One version manifested itself in Afghanistan in the late 1980s. The other is the idea of radical jihadi Islam, or "al-Qaedaism," as some experts call it, which predates the al-Qaeda organization.

Terrorist attacks continue to inspire, but these days rhetoric is at least as important in spreading the al-Qaeda ideology. Under the persistent threat of capture, experts say, al-Qaeda leaders' ability to plan attacks appears hindered. Rather, they have become a sort of public relations branch, regularly releasing videotapes in which they encourage the faithful to continue their resistance against "the Americans and their crusader allies." As Abu Musab al-Zarqawi, the late leader of al-Qaeda in Iraq described, "We are in a media battle...for the hearts and minds of Muslims."

The Iraq War has proven a powerful recruitment tool for al-Qaeda. European intelligence estimates some 1,000 Muslims from countries including Belgium, Britain, France, Germany, Spain, and Switzerland have traveled to Iraq to join the fight against the U.S.-led coalition there. Beyond attracting new fighters, experts say the Iraq war has helped drive many to take up al-Qaeda's cause. "Time and again," Gerges says, "Iraq has emerged as the most potent ideological weapon in al-Qaeda's strategy." He also notes an increase in "self-generating" cells and networks which aim to carry out attacks in the name or spirit of al-Qaeda, but are not under the direction of al-Qaeda leaders.

There's no set formula. Experts say members of such cells may find each other in radical mosques, religious meetings, or on the Internet. Sometimes they are encouraged by a leader and sometimes not. Some members have criminal histories and others have clean records. Nevertheless, there are some qualities that most groups share. Self-generated cells usually raise their own funds, terrorist experts say. The group that attacked the Madrid subways generated $10,000 to $15,000 partly by trafficking drugs and selling counterfeit CDs. The group that attacked London's transit system only needed $2,000, a sum that likely came from personal savings. In contrast, the 9/11 attacks cost an estimated $500,000, which came from an established financial network that has since been dismantled.

Individuals in self-generating cells may not be specifically inspired by bin Laden or Zawahiri, but they are compelled by radical Islamic ideology and see violence as a means to further this cause. These cells often plan attacks near their homes, meaning the individuals already know their target and can easily blend into the general population.

• Miami—On June 22, 2006, FBI agents arrested seven members of an alleged homegrown terrorist cell. They accused the group of plotting to bomb Chicago's Sears Tower, and other, smaller targets within the United States, as well as providing support to al-Qaeda. Though the group's members organized on their own, Attorney General Alberto Gonzalez told reporters they requested funds from and pledged allegiance to al-Qaeda. The severity of the threat posed by the "Miami Seven" has been questioned; even FBI Deputy Director John Pistole told reporters the group's plans were "more aspirational than operational," and several media outlets referred to them as "kooks." Yet experts point out the perpetrators of the 1995 Oklahoma City Federal Building bombing may have seemed similarly crazy when they were plotting their attack.
• Toronto—On June 2, 2006, Canadian officials arrested seventeen young men who had attempted to buy large quantities of explosives, charging them with conspiring to carry out attacks on several targets throughout southern Ontario. Though the group does not appear to have any direct ties to al-Qaeda, experts say it was inspired by the ideology preached by al-Qaeda leaders.
• Los Angeles—In July 2005, as part of a bank robbery investigation, police arrested two men they then discovered were plotting attacks on the El Al airline ticket counter at Los Angeles International Airport, several Jewish synagogues, and a handful of other targets throughout the area. The two men, Haney Washington and Gregory Vernon Patterson, are reported to have converted to Islam and joined an Islamist gang while they were incarcerated for other offenses. Though they had no ties to al-Qaeda, they represent the kind of supporters al-Qaeda leaders hope to inspire.
• London—The July 7, 2005 suicide bombings of London's mass transit system were carried out by a group of young men who were either citizens or residents of the UK. It is unclear how much this group was supported by outsiders. Two months after the attack, Zawahiri released a video in which he claimed al-Qaeda had "launched" the attack, though the Report of the Official Account of the Bombings found "no firm evidence to corroborate this claim."
• Madrid—Though the March 11, 2004 bombings of the Madrid subway system have been attributed to al-Qaeda, it is not clear to what extent the individuals who planned and carried out the attacks were linked to al-Qaeda leadership. Nevertheless, a Spanish judge indicted Osama bin Laden in connection with the bombings.

In waging the "war on terror," or any war for that matter, it is helpful to have a clearly defined enemy. Combating an ideology is more difficult. "The policy of capture and kill has been ineffective," says Farhana Ali, an expert on terrorist movements at RAND. "In the short term, it's effective... but in the long term, new groups emerge." She suggests the military campaign to combat terrorism needs to be complemented by a counter-ideology. This requires an understanding of the socioeconomic factors that make people sympathetic to al-Qaedaism as well as the participation of more moderate voices in places where such an ideology is likely to take root. "We need more community religious leaders fighting religious extremism," Ali says.

One place where governments have been slow to provide an alternative message is the Internet. The web is one of the most active breeding grounds for terrorist ideology, and beyond efforts to provide a counter-ideology, governments need to find ways to better prevent terrorists from using the Internet as a means of mass communication. "We've gotten them in the physical battlefield, but in the virtual battlefield I don't think we've been as effective," Hoffman says. "As long as they're communicating, they're continuing to have a presence."