Indeed, the Justice Department has had a mixed record in prosecuting alleged terrorism cell members in the United States; just this week, its first big terrorism conviction was thrown out of court by a federal judge in Detroit.
Such problems have raised questions about how successful the government has been in tracking terrorists, while skeptics ask if the terror threat is being hyped to bolster support for the Bush administration's hard-line approach.
Several U.S. counter-terrorism officials acknowledged that they had no hard evidence that Al Qaeda operatives were living in the U.S. and readying a terrorist attack. But the officials, who have tracked Al Qaeda in the United States and overseas, said they operated every day under the assumption that the terrorist network had not just sympathizers but one or more teams of attackers ready and waiting in the country.
One U.S. official, whose specialty is tracking Al Qaeda, said, "The difference between now and 9/11 is they are now in a rabbit hole. But are they still here? You bet."
Some of the investigations have been underway for months or even years. In others, the FBI, Department of Homeland Security and other agencies are pursuing recent leads generated through electronic intercepts and the capture and interrogation of suspected terrorists overseas and a review of their computers, cellphones and paper documents.
Several of the investigations involve alleged terrorism cells in New York and northern New Jersey, where suspected Al Qaeda operatives have been under intermittent surveillance since the early 1990s.
One focuses on local supporters of prominent Yemeni cleric Mohammed al Hasan al-Moayad and an aide, Mohammed Mohsen Yahya Zayed, who authorities contend have used a Brooklyn-based mosque, ice cream parlor and other businesses to funnel $20 million to Al Qaeda overseas, court documents show.
New York area authorities also continue to investigate whether local sympathizers helped another prominent cleric, Omar Abdel Rahman, the so-called blind sheik, communicate with leaders of an Egyptian-based terrorist organization while Abdel Rahman was imprisoned in Colorado. One U.S. postal employee is being prosecuted in that case.
Additional investigations in the New York region focus on other suspected Al Qaeda cells, as well as operatives believed to be providing clandestine support for alleged Al Qaeda affiliate groups such as Ansar al Islam and Egyptian Islamic Jihad as well as Hezbollah, a global terrorism network of its own, authorities said.
