A secret FBI report obtained by ABC News concludes that while there is no doubt al Qaeda wants to hit the United States, its capability to do so is unclear.
"Al-Qa'ida leadership's intention to attack the United States is not in question," the report reads. (All spellings are as rendered in the original report.) "However, their capability to do so is unclear, particularly in regard to 'spectacular' operations. We believe al-Qa'ida's capability to launch attacks within the United States is dependent on its ability to infiltrate and maintain operatives in the United States."
And for all the worry about Osama bin Laden's sleeper cells or agents in the United States, a secret FBI assessment concludes it knows of none.
The 32-page assessment says flatly, "To date, we have not identified any true 'sleeper' agents in the US," seemingly contradicting the "sleeper cell" description prosecutors assigned to seven men in Lackawanna, N.Y., in 2002.
"Limited reporting since March indicates al-Qa'ida has sought to recruit and train individuals to conduct attacks in the United States, but is inconclusive as to whether they have succeeded in placing operatives in this country," the report reads. "US Government efforts to date also have not revealed evidence of concealed cells or networks acting in the homeland as sleepers."
It also differs from testimony given by FBI Director Robert Mueller, who warned in the past that several sleeper cells were probably in place.
"Our greatest threat is from al Qaeda cells in the United States that we have not yet been able to identify," Mueller said at a Senate Select Intelligence Committee hearing in February 2003. "Finding and rooting out al Qaeda members once they have entered the United States and have had time to establish themselves is our most serious intelligence and law enforcement challenge."
When the secret report was issued last month, on Feb. 16, Mueller testified at a hearing before the same committee that the lack of evidence concerned him. "I am concerned about what we are not seeing," he said.
The report does cite several cases in which individuals have been seen as potential sleeper agents, including a member of the Saudi Arabian Air Force training at Lackland Air Force Base in Texas.
The Saudi was sent home after it was discovered he provided information to al Qaeda figures in Saudi Arabia, including "coordinates on landmarks in the US," the report says.
"It's not surprising because we believe the Saudi military is infiltrated at the junior officer level in Saudi Arabia," said Dick Clarke, a former White House counterterrorism czar and now an ABC News Consultant. "And there are so many of them who come here for training."
The report also says al Qaeda is shifting tactics because its leaders are aware of profiles singling out adult Arab males.
"Al-Qa'ida places a premium on operatives who are not, or at least appear not to be, Arab, particularly those with European or Asian features, according to various detainee reporting," the report reads. "Detainees also report that al-Qa'ida is interested in recruiting US citizens to participate in US operations, particularly African-American converts to Islam."
But the report continues that "US recruits are hard to find and al-Qa'ida detainees have reported that US citizens can be difficult to work with, one senior detainee claimed that US citizens and others who grew up in the West, were too independent and thought they knew more about US operations than senior planners."
In addition, women and married couples with children are being actively recruited, according to the report.
"A senior al-Qa'ida detainee instructed an operative who is currently in US custody, to settle in the United States with his family and maintain a low profile before eventually conducting an attack," the report reads. "Al-Qa'ida operatives have also married US women to obtain US visas and foreign documentation from other countries, according to sensitive reporting."
The FBI says it takes no solace in the lack of evidence, or about what it is not seeing.
"Individual operatives who possess a clean passport, have not come to the attention of intelligence agencies overseas, and lack a criminal record are unlikely to attract the attention of security agencies in the United States, unless they are in contact with known extremists," according to the report. "Al-Qa'ida has altered its operative profile, making it more difficult to screen visa applicants at embassies and individuals entering the United States at airports and other border crossings."
And the report suggests that instead of actual sleeper agents, lying in wait, al Qaeda may rely on disaffected Americans or other sympathizers, who might pick easier, softer targets such as shopping malls.
Clarke warned, "We have reason to believe that techniques like that and others we shouldn't talk about are well known to terrorists around the world."
ABC News' David Scott contributed to this report.