"There may be loosely knit individuals -- not cells per se -- but loosely knit individuals associated with (al Qaida)" still free in the United States, one administration source close to the investigation said.
Al Qaida, or "the base," is the shadowy terrorist organization founded and financed by fugitive Osama bin Laden.
The FBI hopes to have more specific information about possible future attacks once an eight-person team dispatched to Afghanistan completes the questioning of about 15 al Qaida members captured in the fighting. The fighters are being held at a U.S. Marine-built detention area near Kandahar, southern Afghanistan.
The FBI team was supposed to conduct a quick, low-profile visit, one U.S. official said. Its purpose is "primarily to obtain information on the outstanding fugitives and other individuals involved in the Sept. 11 attack," according to the official.
The State Department and FBI have released a list of the 22 "Most Wanted Terrorists," and the team is looking for any information about anyone on the list, including bin Laden.
The team has also been given the task of obtaining "additional information about the (Sept. 11) attacks and any future possible attacks," the official said.
Certainly, al Qaida allies in Afghanistan at one time believed there were more attacks to come in the United States.
John Walker, a 20-year-old American captured in Afghanistan along with other al Qaida fighters, has told his interrogators as much. However, U.S. investigators so far have not given much credence to his information, saying he was too low-level a member to know much about the terrorist group's activities.
A more knowledgeable source would be Taliban leader Mullah Mohammad Omar, who is thought to be still at large in Afghanistan following the collapse of his regime. In an interview with the British Broadcasting Corp. in November, Omar spoke of a "plan" to launch further attacks against the United States.
"The plan is going ahead and, God willing, it is being implemented," Omar said. " ... If God's help is with us, this will happen within a short period of time. Keep in mind this prediction."
But then Omar shaved his bets, modifying his remarks to suggest that any future catastrophe for the United States might come from an act of God, instead of an act of terror. "This is not a matter of weapons," Omar told his BBC interviewer. "We are hopeful for God's help. The real matter is the extinction of America. And, God willing, it will fall to the ground."
Attorney General John Ashcroft's "zero tolerance" policy since the Sept. 11 attacks was designed to quickly disrupt terrorist networks in this country rather than charge individual members directly with the attacks.
Under the policy, law enforcement officials examined anyone caught up in the nationwide FBI investigation and charged them with an unrelated crime if they were found to be in violation of any law.
This gave the Justice Department breathing room to gather evidence for more serious charges and at the same time took what investigators believe were potential terrorists off the streets.
For instance, many of those charged since Sept. 11 have not been accused of participating directly in the plot that led to the attacks. Instead, they have been charged with participating in long-running false ID operations that the Sept. 11 hijackers tapped into to obtain U.S. papers.
Slightly more than 100 people have been charged with federal violations, about a dozen of those under seal because of judge's orders. The names of all those arrested on federal charges, except those charged under seal, have been released.
Another "handful" of people are being held on "material witness" warrants issued by a U.S. judge in New York. Their names, and the names of more than 600 people who have been detained by the Immigration and Naturalization Service because of improprieties in their immigration status have not been released.
Ashcroft has indicated several times that U.S. investigators believe a few of those in U.S. custody are members of al Qaida.
However, only one suspect in the United States, Zacarias Moussaoui, has been charged directly in the plot that led to the Sept. 11 terror attacks.
Moussaoui, a 33-year-old French citizen of Moroccan ancestry who had been living in Britain, was named on a 6-count conspiracy indictment last week in Alexandria, Va.
Moussaoui was taken into U.S. custody in Minnesota in August because of his immigration status. However, U.S. officials charge that he essentially went through the same training and preparation as the 19 hijackers who are suspected of participating in the attacks.
Wednesday, Moussaoui appeared before a U.S. magistrate for an initial hearing. He is scheduled to undergo arraignment before U.S. District Judge Leonie Brinkema on Jan. 2. Brinkema will also oversea Moussaoui's trial if he does not cut a deal with federal investigators in exchange for his cooperation.
By President Bush's count, U.S. allies have arrested about 300 people abroad and charged them in connection with al Qaida operations.