The White House on Tuesday forcefully rebutted reports that the data behind this week's specific terrorism warnings and security upgrades was dated.
The New York Times is reporting in Wednesday's editions that while the surveillance of U.S. buildings appears to date to before Sept. 11, 2001, a separate stream of intelligence late last week pointed to an imminent attack, according to officials.
But intelligence agencies have been unable to reach a consensus on whether the unusually detailed documents recovered in Pakistan reflect a defunct terror plot or one that might have been successfully interrupted.
"We have very little information — target information, but not the full breadth of the plot or possible plot," one law enforcement official said Tuesday, speaking on condition of anonymity because parts of the investigation are classified.
Some of the information seized about the surveillance of five financial buildings in New York, Washington and Newark, New Jersey, was as much as four years old. But the Bush administration maintains it was essential to alert the public as soon as it was found because al Qaeda planning sometimes precedes actual attacks by as much as five years.
"These are serious folks," Homeland Security Secretary Tom Ridge said Tuesday. "They're patient folks."
Counterterrorism experts believe planning for the Sept. 11, 2001, attacks began in 1996. They also believe a terror suspect photographed American government buildings in Nairobi, Kenya, and drew sketches of potential targets for Osama bin Laden in 1993 — long before al Qaeda detonated a truck bomb in August 1998 near the U.S. Embassy there, killing 257.
Law enforcement and intelligence officials said some computer images of the surveillance by al Qaeda in the United States had been changed as recently as January, although one official explained that investigators can't determine whether something was added or how else the image might have been modified.
Many of the paper documents recovered were not dated, so analysts worked backward trying to match particular descriptions of security at these financial buildings with a particular moment in time, to determine when the observations were made.
"There is physical descriptive data that might let them date some of this," the law enforcement official said.
The Bush administration denied any suggestion that raising the terror alert in New York and Washington so quickly after the Democratic convention was politically motivated. "We don't do politics in the Department of Homeland Security," Ridge said.
U.S. officials conducted a special intelligence briefing Sunday for Democratic presidential nominee John Kerry. A spokeswoman declined to say whether Kerry as president would have authorized public warnings based on the same information.
"Senator Kerry never comments directly or indirectly on the information he receives in intelligence briefings," spokeswoman Debra DeShong said.
The warnings prompted authorities to raise the terror alert level in those cities to a high level. Police closed streets, erected barricades and dispatched heavily armed officers to patrol potential targets.
Federal investigators are working on the assumption that the plot is continuing, said a senior Justice Department official, speaking on condition of anonymity. Two counterterrorism officials, also speaking anonymously, said information and evidence uncovered suggests that terrorists were recently using the information from the surveillance activities.
Law enforcement agencies are searching for the al Qaeda operative who wrote the surveillance reports, and CBS News National Security Correspondent David Martin reports officials who have read the documents say the author was clearly and English speaker.
The intelligence behind the warnings — including detailed surveillance photos, sketches and written documents — came from sources that included a seized laptop and discs as well as interviews after the mid-July arrest of a young Pakistani computer engineer, Mohammad Naeem Noor Khan.
Shortly after Khan's arrest, police in Pakistan arrestedof Tanzania, one of those indicted in the 1998 U.S. embassy bombings in eastern Africa. Ghailani, also known as "Fupi," was cooperating with authorities and corroborated material found in the surveillance documents, according to one senior Justice Department official, speaking on condition of anonymity.
The information recovered in Khan's arrest also included references to the Nasdaq and American Stock Exchange buildings in New York and the Bank of America building in San Francisco, said one counterterrorism official, speaking on condition of anonymity. Two other facilities in New York and undisclosed buildings in Washington and New Jersey also were mentioned, the official said.
First lady Laura Bush told the CBS News Early Show she traveled to New York City this week, despite the terror threat, "to let everybody know who works there that I think it's safe."
"I mean these are very anxiety provoking times and when you — when the terror alert level is raised it is very anxiety provoking, especially for people here and in Washington and in other big cities," Mrs. Bush said. "But it's also really important for us to go on about our business."
A spokesman for the Homeland Security Department, Brian Roehrkasse, said information about these other buildings was limited or was so generic that it did not suggest the same level of surveillance as the five buildings named in Sunday's alert.
Whether they are connected to the intelligence uncovered in the arrests of Khan and Ghailani, or the terror alerts in the United States, is unclear, but Pakistan and Britain have made a round arrests of terrorism suspects this week.
In Britain,in an anti-terrorist sweep faced questioning Wednesday following a series of raids which police said were part of a continuing investigation. Under the Terrorism Act, passed after Sept. 11 attacks, police can detain the men for up to two weeks without charge, reports CBS's Charlie D'Agata.