Information obtained from terrorists regarding potential attacks on certain U.S. financial targets could be up to four years old, but officials were warning that Al Qaeda (search) is patient and takes time to plan attacks.
Officials said they had not yet found hard evidence that a terrorist plot or preparatory surveillance operations were still under way. But Homeland Security Secretary Tom Ridge (search) said Tuesday there was some information discovered that has been updated as recently as January of this year.
"We know this is an organization that plans in advance, that prepares and is patient," Ridge said during a press conference in New York on Tuesday. "If anything else, the thoroughness of this information reflects the seriousness … it also speaks to their sophistication as an operation … these are serious folks, it speaks to their resolve."
Late Monday, officials said there were "several" more banks and financial institutions included in the warning, most if not all of them in the New York area. Among those are the American Stock Exchange (search), and Nasdaq, the bulk of whose operations are in Times Square, far uptown from Manhattan's financial district.
Sources confirmed to FOX News a list of more targets that have been notified of specific threats, including: Morgan Stanley, Lehman Bros., Goldman Sachs, the Federal Reserve Bank, Bear Stearns, AIG, MetLife and JP Morgan Chase.
The TransAmerica building (search) — the well-known pyramid-topped skyscraper that defines San Francisco's skyline — is FOX News' first confirmation of a potential West Coast target. Multiple sources from law enforcement and defense corners have told FOX News that information on this site was found on the Al Qaeda computer confiscated in Pakistan.
The federal government raised the color-coded terror alert Sunday for New York City, Washington, D.C., and northern New Jersey when it announced that terrorists had recently cased the New York Stock Exchange (search) and The Citigroup Center (search) in Manhattan, the International Monetary Fund (search) and World Bank (search) buildings in Washington and Prudential Financial Inc.'s (search) headquarters in Newark, N.J.
The information came largely from a Pakistani computer engineer captured last month and most of the information was amassed in 2000 and 2001. Officials have emphasized that the plot was more along the lines of operational planning, not a finalized, planned attack.
Investigators are looking at a possible link between the Pakistani militant and the Kenya and Tanzania bombings in 1998, said a senior Justice Department official.
A White House spokesman said the intelligence was detailed and "chilling," even if some of the information appeared to be old.
"I think you have to keep in mind Al Qaeda's history of planning attacks well in advance and then updating those plans just before attacking," said spokesman Scott McClellan.
Ridge said Tuesday that it was imperative for the federal government to publicize the terror information and raise the alert level where the most threat lay.
"This is actionable information," Ridge said, adding that experts are still reviewing "quite a bit of evidence" and intelligence reports in the hope "we can get some insight into what they [terrorists] were looking for and the means [by which] they got that information" about the targets.
Ridge said law enforcement has its "eyes on" possible suspects here in the United States and can't rule out the possibility of sleeper cells.
"In this day and age in a country that's as open and diverse as ours … we just assume there are operatives here," Ridge said, adding that he has no doubt that "they're here, they're looking to attack us and we need to do what we can every single day to detect and deter" any attack.
Meanwhile, the New York Post reported that investigators suspect terrorist moles worked at Citigroup's 59-story building at Lexington Avenue and 53rd Street in Manhattan and Prudential's buildings to case the skyscrapers as potential targets of car or truck bombs.
Federal agents want to comb through employee records of the businesses that operate in the buildings to try to identify the moles, law enforcement sources said. Investigators hope that names of ex-employees will turn up on watch lists or other rosters of suspected terrorists.
Officials who examined the information concluded that the most recent surveillance of the buildings was done in January. There was additional surveillance last year, a law-enforcement source said.
A senior Justice Department official said federal government investigators are operating under the assumption that the plot was ongoing. The official said there are indications that the surveillance was detailed enough that people who work in the buildings might have knowingly or unknowingly assisted - perhaps by inadvertently giving out information.
Terrorism experts cautioned that despite all the security precautions, Al Qaeda's biggest trademark is the element of surprise.
"Al Qaeda's tactics have always been to attack where they're not expected rather than where they're expected," terror analyst Eric Margolis told FOX News, noting that before Sept. 11, officials were sure the intelligence they had pointed to a possible attack somewhere in Europe, not New York and Washington. "We have to be extremely vigilant but I don't think this is what the CIA would call 'actionable intelligence' information.
"Al Qaeda's sort of achieving its goal right now, which is giving America a national nervous breakdown," Margolis added.
No 'Fortress America' Here
Workers were confronted with ID checks and bag searches as they headed for work Monday. Police said the measures would remain in effect Tuesday and would be reviewed daily.
"You realize that's the world you live in, and you deal with it," said Kenneth Polcari, a trader at the New York Stock Exchange, one of many workers who filtered into the Wall Street building Monday.
Ridge, New York Mayor Michael Bloomberg, Gov. George Pataki and New Jersey Gov. James E. McGreevey met Tuesday with financial executives from affected companies to discuss security concerns.
"We have made it much more difficult for the terrorists to achieve their broad objectives. ... We will not become fortress America," Ridge said.
"New York City is open for business … and it is going to stay open," Bloomberg added. "Nobody is going to dissuade us from making this our home. Nobody's going to change our minds this is the place where they have the ultimate opportunity."
"The best days for New York are yet to come and the terrorists will not win," Bloomberg added.
Bloomberg and Pataki rang the opening bell at the stock exchange Monday and visited the Citigroup building with first lady Laura Bush and her twin daughters in the afternoon.
Authorities in Washington, D.C., announced plans to block portions of Independence and Constitution Avenues — major traffic arteries that run on either side of the Capitol grounds.
Washington police checked ID cards as employees filed into the World Bank headquarters; inside, security guards checked them again. Across the street, guards at the International Monetary Fund swept the underside of cars with detecting devices as they entered the garage.
"I'm concerned, but we have to carry on as normal," said IMF employee Shirley Davies.
Police closed Manhattan streets around Grand Central Terminal and banned trucks from some bridges and tunnels. Trucks passing landmarks or traveling on major thoroughfares also were subject to random searches.
Officials set up concrete barriers and police teams around the 24-story Prudential building in New Jersey, where about 1,000 employees work. They showed identification to get into the building and its underground parking garage.
Prudential Chairman Arthur F. Ryan said the "overwhelming majority" of employees reported to work. "Everything we've heard so far has been reinforcing. 'We're with you.' That's basically what we've heard from most of them," Ryan said.
Security Stepped Up Across the U.S.
Security measures were heightened in downtown Los Angeles and in the Century City complex where high-rise buildings and financial institutions are located.
"We have received no credible information to indicate any of these threats are directed against Southern California. However, we are going to continue to remain on a heightened state of vigilance," Los Angeles Mayor James K. Hahn said.
The Chicago Board of Trade closed its visitors center in response to the threats, and the Federal Reserve Bank of Chicago also heightened security.
Chicago Mercantile Exchange spokeswoman Anita Liskey also wouldn't comment on specific security measures at the futures market, one of the largest in the world, but employees in the building said they had noticed changes.
"There's more security guards," Mercantile clerk Jenna Fowler said, pointing to a guard standing outside a window. "It makes me scared that it's a financial institution, but there's a lot more security than there was last week."
FOX News' Bret Baier, Ian McCaleb, Liza Porteus, Anna Stolley and The Associated Press contributed to this report.