GWEN IFILL: Finally tonight, another in our series of conversations about the state of al-Qaida.
Last week, we heard from a former CIA field officer and top counterterrorism official, who said he believes al-Qaida is regaining momentum -- tonight, a different view.
Margaret Warner has that.
MARGARET WARNER: Marc Sageman has spent most of his career studying terrorists and extremists networks like al-Qaida. In the 1980s, as a CIA case officer in Pakistan, he worked closely with al-Qaida's precursor, the Afghan mujahedeen, in their fight against the Soviets.
Sageman became a forensic psychiatrist after that and began conducting studies on what motivates young people to join terror movements. He's produced two books on the topic. The second, "Leaderless Jihad" in 2008, drew controversy for describing the global movement as increasingly disorganized.
MARC SAGEMAN: What we see here is a number of plots over 20 years.
MARGARET WARNER: At his home in Washington, Sageman showed us his latest research, a survey of all terror plots against the West in the past 20 years.
His graphs show, the recent peak actually came in 2004, with 10 plots, including the Madrid train bombings. The number steadily declined each year after that, to just three in 2008. He concedes that 2009 saw a slight uptick with five plots, including the failed Christmas Day airliner bomb attempt.
I began by asking Sageman whether that 2009 increase and the Christmas Day airline bomb plot showed al-Qaida has redoubled its efforts to attack the U.S. homeland.
MARC SAGEMAN: I think central al-Qaida's desire to attack the homeland has always been very strong and has not diminished. The problem for al-Qaida central is that its capabilities are very low.
MARGARET WARNER: What has al-Qaida evolved into today? What we loosely call al-Qaida, what is it really?
MARC SAGEMAN: Al-Qaida right now is a lot of leaders hiding full-time from Predator missiles in Pakistan. They still have a presence on t he Internet. They release audiotapes very rarely, maybe once every other month or so. But, operationally, they are very limited.
And they really don't have the type of command-and-control that they did have in 2001 or even 2006, a large -- the last large al-Qaida plot, namely the liquid bomb case.
MARGARET WARNER: So, what else is there?
MARC SAGEMAN: There are many other terrorist organizations vying for control of this large movement.
MARGARET WARNER: Self-starter offshoots like al-Qaida in the Arabian Peninsula based in Yemen, which claimed responsibility for the Christmas Day bomb attempt.
Sageman insists neither that group, nor any of the other regional al-Qaida-inspired outfits has the ability to organize and carry out attacks of the size and lethality of 9/11.
Should we feel threatened by the fact that, in a country like Yemen now, we have seen a plot directed at us?
MARC SAGEMAN: Yes, of course we should feel threatened by all the plots emerging, not only from Yemen, but, also, there was one plot emerging out of Somalia in Australia this past summer.
And so now we see plots not just coming from Pakistan, but also from other parts in the world. But we have to understand that most of those plots are people from the West going to those places, some of them getting training, and then coming back to the West.
MARGARET WARNER: Now, you, as a psychiatrist, have really studied this phenomenon. What does account for this seemingly endless supply of recruits? You call them lone wolves.
MARC SAGEMAN: Yes, we see more lone wolves now. And they have a strong presence, strong participation in jihadi chat rooms. And that's where the radicalization really takes place.
And, by radicalization, I mean a two-step process. One is joining this protest counterculture, which right now is inspired by the utopia projected by al-Qaida. And then the second step is a rejection of this protest counterculture and turning to violence, because they feel that this protest counterculture, which is still legal in a Western liberal democracy, is just not efficacious enough. It is just talk, talk, talk.
MARGARET WARNER: And so how does the West or should the West combat it?
MARC SAGEMAN: The West should focus on those that are about to turn violent, as opposed to trying to suppress the protest counterculture.
MARGARET WARNER: But how in practical terms?
MARC SAGEMAN: You know, it is a very difficult problem. There's no easy answer.
And what we need to do is to monitor those people who emerge out of this protest counterculture that start behaving certain ways that become suspicious, and you focus more on their activities. And once they cross a line, you arrest them.
MARGARET WARNER: Are you talking about a major domestic spying operation?
MARC SAGEMAN: I don't advocate a large domestic spying system. But when people start rejecting their old friends from the protest counterculture and start doing things odd, people within the protest counterculture know that they are up to no good. They often avoid them. They themselves separate themselves from the protest counterculture.
In a sense, we have to use these protest countercultures to help us defeat this political violence.
MARGARET WARNER: I asked him how worried he was that these regional groups training inexperienced young radicals like the failed underwear bomber would one day carry it off.
MARC SAGEMAN: It's inevitable that they will succeed, at least in one plot. What we need to do is to limit the number of people who may succeed and to limit the damage of any success.
We have to be perfect 100 percent in order to prevent them from doing that. We're not perfect. Let's not kid ourselves. So, it is very, very difficult to do. But, with time, the appeal of this type of utopia is going to diminish.
MARGARET WARNER: And what gives you confidence it will burn out?
MARC SAGEMAN: There are a lot of indications it's already burning out.
The support for terrorism, for violence, both in Muslim expatriates in the West and Muslims in the Middle East or South Asia, is diminishing, and dramatically diminishing. And strangely enough, ironically enough, in the past, when we have seen this contraction of a protest counterculture, the violence is increased at the tail end of that movement.
So, perhaps what we have seen, this uptick this past year, may be due to the last remnants who are, in a sense, frustrated by the lack of effectiveness of the protest counterculture, and decide to do things themselves, out of, you know, certain moral outrage that is happening in the world.
MARGARET WARNER: Marc Sageman, thank you very much.
MARC SAGEMAN: Thank you.