Authorities check 'credible' terrorist threats to NYC, D.C.

 Federal authorities investigated "specific, credible but unconfirmed" threats Thursday night involving possible plots to attack New York City and Washington around the 9/11 anniversary, the Department of Homeland Security said.

The threat involving possible bombings was shared with New York and Washington police.

The threat information was about three people who may have been dispatched to the U.S. to meet with associates to carry out the attacks, said a federal law enforcement official who was not authorized to speak publicly and asked not be identified.

President Obama was briefed about the matter Thursday morning and received updates during the day.

Department of Homeland Security spokesman Matt Chandler said documents recovered from the raid in May on Osama bin Laden's compound in Pakistan revealed al-Qaeda's interest to strike the U.S. on meaningful dates.

"In this instance, it's accurate that there is specific, credible but unconfirmed threat information," Chandler said. "As we always do before important dates like the anniversary of 9/11, we will undoubtedly get more reporting in the coming days."

New York Mayor Michael Bloomberg said the threat, while credible, was "not corroborated." He urged New Yorkers to go about their business as usual.

"There is no reason to change any of your routines," he said at a news conference Thursday night. He also urged citizens to report anything suspicious.

New York Police Commissioner Ray Kelly said the department was extending officers' shifts and would be increasing police presence on the streets.

He also said officers would be conducting additional bag checks at subway stations and warned citizens they might encounter police checkpoints throughout the city.

The threat information did not prompt an immediate elevation of the national threat level.

Earlier Thursday, Homeland Security Secretary Janet Napolitano said there was "lots of chatter" among known terror associates and on jihadi websites in the run-up to Sunday's 10th anniversary of the attacks that killed nearly 3,000 people at the World Trade Center in New York, the Pentagon in Arlington, Va., and Shanksville, Pa.

In the past several days, federal, state and local authorities have dispatched thousands of personnel to sensitive locations in New York City, Washington and elsewhere to guard against possible disruptions.

Even without a confirmed threat, officials said the heightened state of alert was necessary because of al-Qaeda's stated intent to strike on the 9/11 anniversary.

Attorney General Eric Holder said there would be noticeable increases in law enforcement at national landmarks and public gatherings commemorating the anniversary.

Napolitano said more air marshals would be riding commercial airlines, which al-Qaeda hijackers converted into guided missles during the 2001 attacks.

Amtrak is stepping up screenings of passengers and baggage throughout its rail system, including the heavily traveled Northeast corridor.

Information seized from bin Laden's compound shortly after the terrorist leader was killed by Navy SEALs revealed that al-Qaeda considered the U.S. rail system as a possible target.

John O'Connor, Amtrak vice president and police chief, said the railroad is expanding patrols and bomb-detection teams.

White House chief counterterrorism adviser John Brennan said U.S. efforts in the aftermath of 9/11 — specifically the elimination of top-level terror leaders — have "made it much more difficult" for operatives to launch large-scale attacks.

Al-Qaeda "has taken it on the chin," Brennan said.

The death of bin Laden, the architect of 9/11, was the most significant and symbolic of the organization's losses.

Brennan said the material shows the al-Qaeda chief was "a little out of touch about how debilitated his organization was" after years of battle with U.S. and other forces.

"He was pushing for these major types of attacks," Brennan said. "I think his lieutenants were trying to tell him, 'We know what you want to do — great aspirations — but our ability to do that is degraded because we are losing people.'"

U.S. officials combing data from bin Laden compound, Holder says

Attorney General Eric Holder predicted Wednesday more names will be added to U.S. terrorist watch lists as law enforcement agencies review the evidence gathered in Pakistan after the raid on Osama bin Laden's compound on Monday.

"The material that was seized from that residence is being reviewed by an inter-agency team: CIA, Justice, other intelligence agencies, other law enforcement agencies are contributing people and machines to go through that material. As we glean information from that material, we will make appropriate decisions with regard to who might we add to the terrorist watch list, the No Fly list, all those things," Holder told the Senate Judiciary Committee.

Sen. Charles Schumer, D-New York, asked, "You expect you probably will add people as a result of what you got?"

Holder replied, "My guess is that we probably will."

The attorney general also told lawmakers the Justice Department is looking at the possibilities of retaliation from terrorists in the short term.

"I had a conference call with all of the United States attorneys, I believe on Tuesday maybe on Monday, going through with them 'think steps' that we wanted them to take, making sure they as well as all the federal investigative agencies, were on their toes and being mindful of the fact that this is a difficult time for this nation after the death of bin Laden," Holder said.

Department of Homeland Security Secretary Janet Napolitano also told Congress Wednesday a "number of actions" have been taken in response to the killing of bin Laden, among them "surging some resources" to U.S. ports, airports and borders.

"These include issuing advisories to fusion center directors, Homeland Security advisers, major city chief intelligence commanders, private sector critical infrastructure owners and operators and other law enforcement entities. We are and have been reviewing all open cases of potential al Qaeda core, AQAP (al Qaeda in the Arabian Peninsula) and AQIM (al Qaeda in the Islamic Maghreb) operatives possibly in the U.S. in conjunction with the FBI," she said at a Senate hearing.

"We are continuing to strengthen our recurrent vetting for visa, asylum and other benefit applicants and recipients in cooperation with the intel community. We are deploying additional officers to non-secured areas at our large airports, the so called category X airports and we are providing additional info to all air carriers," Napolitano added.

Sen. Joe Leiberman, the Connecticut Independent who is chairman of the Homeland Security and Governmental Affairs Committee, asked Napolitano about the data removed by the Navy SEALs from the bin Laden compound. "I assume that as this material is gone over, anything related to Homeland Security will be shared immediately with your department?" he asked. Napolitano responded, "It is being shared (already)."

The new National Terrorism Advisory System, which replaced the color-coded terrorist threat alert last month, has not been changed in the aftermath of last weekend's raid and recovery of computers, hard drives, DVDs, thumb drives and storage devices.

"Right now, we do not have any specific or credible intel that would lead us to issue an alert under this new system, realizing that under this new system the baseline is already elevated," Napolitano said. "In other words, the baseline assumes a continuing and evolving terrorist threat against the United States. We continue to review on an ongoing basis all materials seized during the operation as well as new intel that may be coming in, and I stand ready to issue an alert should intel or information emerge that warrants it under the advisory, the new advisory system," she added.

Sen. Ron Johnson, R-Wisconsin, questioned the purpose of the new system. "If we're always on the same constant level of alert, that just degrades over time. Again, I'm just kind of scratching my head," he said.

Napolitano responded, "If I might, senator. That was the problem with the color code, because we were always at orange and nobody paid any attention. The purpose of the advisory, in my view, is to communicate facts and information so people know what to do. So if we elevate the advisory it will be followed by information, what are the facts that we can disclose, what can people do to protect themselves and their families, where can people go to get updated information, how can people help us help them. So it's not just to be alert.

"We are always on alert, that's the elevated base, but now we would be providing additional facts based on the intel we receive that tells people what to do."