Are terrorist cells still in the US?

New charges that a Maryland paramedic gave "material support" to terrorists raise anew troubling questions for post-9/11 America.

Do extremist cells still exist in the United States? If they do, how much progress is being made to route them out?

The homegrown nature of the July attacks in London as well as the arrest of a man in Zambia on charges that he'd tried to set up a terrorist training camp in Bly, Ore. in 1999, gives the questions extra salience, according to terrorism experts.

Their assessments of the law enforcement's success rate are mixed. Critics note that most of the suspected terrorists arrested in the US so far were not engaged in any active plan to harm the US. Some, like the newly charged paramedic Mahmud Faruq Brent, had allegedly gone for training in camps in Afghanistan or Pakistan, but mostly they were caught bragging to undercover agents - who openly encouraged them - about their willingness to engage in jihad.

At the same time, analysts point out that the nature of Al Qaeda has changed so much in the light of aggressive law enforcement tactics since 9/11 that the traditional "sleeper cell" model may no longer be attractive to al Qaeda here in the US. As a result, capturing potential terrorists may be the best thing the FBI can be doing right now.

"Measured against [FBI director Robert] Mueller's very confident assertion that there are hundreds of individuals who are members of sleeper cells in the US, these arrests don't indicate to me that we are making progress," says Michael Greenberger, director of the Center for Health and Homeland Security at the University of Maryland. "At the same time, I sympathize with the need to nip terror in the bud and it may very well be that indictments that focus on proposed activities or bragging about future activities may be effective. But we also have to wait to see what the facts in each case were."

Brent was arrested as a result of a sting operation. His former martial arts teacher, a jazz bassist from the Bronx named Tarik Shah, set up the encounter with the FBI shortly after he himself was arrested in May on charges that he gave material support to terrorists. Prior to 9/11, Mr. Shah had taught martial arts at a mosque in Beacon, N.Y. and Brent was one of his prize pupils.

Terrorism experts say that martial-arts training can be the first step in Al Qaeda's elaborate recruitment process. The most able and dedicated are singled out, invited to weekends that involve things like white water rafting - or as in the case of the Virginia Jihad Network, paintball battles in the woods. That creates bonding and allows recruiters to identify those that are especially aggressive or have leadership qualities and aids in indoctrination. Eventually, this process leads to the terrorist training camps in Afghanistan and Pakistan.

According to the indictment, Brent had ties to the Virginia Jihad Network, the leaders of which were convicted in March 2004 and are serving lengthy prison sentences. It was through them that Brent allegedly made his way to Pakistan to one of the terrorist training camps there.

Shortly after Brent's old friend and teacher Shah was arrested in another FBI sting, Shah turned informant and set up a meeting with Brent at a hotel in Maryland, according to the indictment. During the meeting, Shah indicated that he wanted to go overseas to a training camp, and Brent encouraged him. But Brent said it would be difficult to help him because his "only connect" was "doing time now." He also said in the post-9/11 climate it was hard to know whom to trust anymore. "We don't know who is who," the indictment quotes him as saying in a taped conversation. "We were not in a position to make new friends."

Experts say such comments indicate the success law enforcement has had in creating a "hostile operational environment" for any sleeper cell like the one responsible for the 9/11 attacks. And that has markedly changed Al Qaeda's style in the US.

"Not so many people are going back and forth between borders. They're avoiding communications that can be intercepted, exchanges of money that can be tracked," says Brian Jenkins, a senior terrorism expert at the RAND Corp. in Santa Monica, Calif. "All of these are dangerous."

But all this also makes them harder to detect.

The fact that neither Shah nor Brent were actively involved in any plans fuels critics' concern that the FBI is targeting "B" or "C" potential recruits while more dangerous sleeper cells may be lying in wait - those that are more careful about their new friends.

At the same time, experts note that federal authorities are under "great pressure to move in early and operate preventively or preemptively."

"That means that as opposed to waiting for full-fledged conspiracies, they may be picking up individuals when they are still in the early part of this [recruiting] trajectory. They may have only taken a few steps down the path," says Mr. Jenkins. "But if you're going to wait until there are mature terrorist plans, then that runs a risk. And in this post-9/11 environment, authorities are unwilling to take that risk."