Fandy is a senior fellow at the Baker Institute and a specialist on Middle East politics, as well as a professor of Arab politics at the Near-East South Asia Center for Strategic Studies at the National Defense University. In this interview, he discusses the Salafist ideology and its more radical roots in the Muslim Brotherhood and teachings of Sayyid Qutb. Fandy explains how these extreme movements have become more mainstream over time. "If you look at Al Qaeda today in the Arab and Muslim world, it has moved from an extreme to mainstream," he says. "Most young people think being affiliated with Al Qaeda is cool. It is something to be proud of. They're wearing T-shirts with pictures of Osama on it."

Kepel is a professor and chair of Middle East Studies at the Institute of Political Studies in Paris, and the author of The War for Muslim Minds: Islam and the West; and Jihad: The Trail of Political Islam. In this interview, he explains how Europe has evolved from a sanctuary for radical Islamists to a target. Kepel says that second- and third-generation Muslims in Europe have felt discriminated against and that the message of the jihadists have stepped in to fill this vacuum.

A former French intelligence officer, Raufer currently heads the department on organized crime and terrorism at the Institute of Criminology at the University of Paris. In this interview, he recounts the history and ideology of Salafism, and he explains the difference between the French and American methods of fighting terrorism. "We are astonished when we see, when we hear, when we read what the present American administration describes as Al Qaeda," he tells FRONTLINE. "For God's sake, they describe this as some kind of an Irish Republican Army except that, instead of being Catholics, they are Muslims."

From 1993 to 1996, Michael Scheuer, a 22-year veteran of the CIA, headed a special unit the agency set up to track Osama bin Laden. Scheuer, who retired from the CIA in November 2004, has authored two books under the pen name Anonymous: Imperial Hubris: Why the West Is Losing the War on Terror; and Through Our Enemies' Eyes: Osama bin Laden, Radical Islam, and the Future of America. He tells FRONTLINE that he was not surprised that the investigation of the Sept. 11 attacks led to Europe. "We had a very difficult time, as one intelligence agency to another, convincing the Europeans that bin Laden and Al Qaeda were really a threat," he says. Scheuer also discusses the policy of rendition, whereby the clandestine services capture suspects and send them to third countries, a policy that he says was "cobbled together" by the CIA. "The back end has never been discussed, has never been settled," he says. "How do we handle the people we capture? The only answer we came up with -- and it's the agency that came up with it and it was blessed by lawyers -- was to take these people to countries that wanted them for their crimes of terrorism."