U.S. investigators have made little headway in identifying suspects who may have had a direct role in the September 11 terrorist attacks beyond the 19 hijackers who died that day. But they have had success in identifying and disrupting support networks in place to help terrorists operating inside the United States.
This week's indictment of five Muslim men in Michigan on charges of helping al-Qaida plan attacks inside and outside the United States is symbolic of where the Sept. 11 investigation is headed.
The five men in Detroit are accused of operating what prosecutors call a terrorist "sleeper cell". They are alleged to have tested security measures at the Detroit airport and established a support network for al-Qaida terrorists to help them obtain fake driver's licenses, passports, and Social Security cards.
Terrorism expert Neil Livingstone, in an interview with VOA News Now, says disrupting the support networks for terrorists is an essential part of making the United States secure from future attacks.
"They may even have had some involvement in the 9-11 attacks, and certainly may have had some type of involvement in planning future attacks in the United States. So this may be a major breakthrough in terms of rolling up an al-Qaida or pro-al-Qaida cell in the United States.
Prosecutors say they found videotapes in an apartment shared by some of the suspects. The tapes included surveillance footage of famous American landmarks like Disneyland in California and the MGM Grand Hotel and Casino in Las Vegas.
That concerns Steven Sloan, head of the University of Oklahoma's Center for the Study of Terrorism also interviewed by VOA News Now.
"The fact remains that it asserts that we are dealing with a very sophisticated global connection over here," he said. "Among things, I would wonder whether they were also surveilling these with video cameras and so forth and using the Internet to do their own virtual surveillance as well as have people in country. So it is a significant concern."
Adding to that concern is a report in the USA Today newspaper that says U.S. officials fear more attacks are likely because they estimate about 20,000 men were trained in al-Qaida camps around the world before September 11.
The latest indictments indicate that federal officials are having much more success in cracking terrorist support networks than they are in identifying anyone else who may have had direct involvement in last September's attacks.
Only one man, Zacarias Moussaoui, has been accused of being part of the September 11 plot. His conspiracy trial is scheduled to begin in January. But a top Justice Department official recently reminded reporters that Mr. Moussaoui has not been charged as the so-called 20th hijacker in connection with the September 11 attacks.
Law enforcement officials are divided over whether the French national was supposed to be one of the hijackers on September 11 or whether he was involved in some other terrorist act that he never got to carry out. Mr. Moussaoui has denied he had any role in the conspiracy.
Part of VOA's series on the September 11 terror attacks.