The Bush administration raised the national terror threat level from yellow to orange Friday, meaning the country is at "high risk" of a terrorist attack.
Attorney General John Ashcroft said there was an "increased likelihood" that Al Qaeda terrorists would attack American targets, either at home or abroad, in mid-February.
He said "specific" intelligence has been received that Al Qaeda may be planning attacks on hotels, apartment buildings and other "lightly secured targets."
The attorney general also said terrorists might seek "economic targets, including the transportation and energy sectors, as well as symbolic targets and symbols of American power."
Fox News learned that the decision to raise the alert level was based on three factors:
• An increase in intelligence pointing to a possible Al Qaeda attack timed to coincide with the hajj, the annual three-day Muslim pilgrimage to Mecca that begins on Saturday.
• An increase in the "sheer volume" of terrorist activity or "chatter." An official said this "chatter" was rivaling that seen before the Sept. 11, 2001 terror attacks.
• U.S. preparation for a possible war with Iraq.
However, the U.S. military buildup for possible war with Iraq was a lesser factor in the decision to raise the threat level, several officials said. "There's absolutely no connection," said Homeland Security Secretary Tom Ridge.
But Rep. Dennis J. Kucinich, D-Ohio, a leading congressional opponent of war with Iraq, said the change in alert level provided evidence that "this march to war, far from making our nation more secure, has raised the threat to Americans."
A few hours after the announcement, the FBI issued an alert to law enforcement and the public for help in finding a Pakistani man identified as Mohammed Sher Mohammed Khan, 36, who it said may have entered the United States illegally after Sept. 1, 2001. The FBI said it had no specific information that Khan was a terrorist — his name and birthdate might be fictitious — but that agents want to question him.
An FBI official, speaking on condition of anonymity, said Khan was not the reason the terror alert level was raised but that he was "one of a number of factors."
Senior White House, Justice and Homeland Security Department officials had considered raising the level for several days, and President Bush approved the decision in a meeting early Friday.
Ashcroft announced the decision at an afternoon press conference. He was accompanied by Ridge and FBI Director Robert Mueller.
"We are not recommending that events be canceled," nor should individuals change their travel, work or recreational plans, Ashcroft said.
Even so, Ridge urged Americans "in the days ahead, take some time to prepare for emergencies." As an example, he suggested that families devise plans for contacting one another if separated by an emergency.
"Terrorist attacks can really take many forms," he said.
"This decision for an increased threat condition designation is based on specific intelligence received and analyzed by the full intelligence community. This information has been corroborated by multiple intelligence sources," Ashcroft said.
"Since September the 11th, the U.S. intelligence community has indicated that the Al Qaeda terrorist network is still determined to attack innocent Americans, both here and abroad," Ashcroft said.
He said that recent intelligence reports had indicated that "Al Qaeda leaders have emphasized planning for attacks on apartment buildings, hotels and other soft or lightly secured targets in the United States."
Ashcroft said the recent bombings of a nightclub in Bali, Indonesia, and of a resort hotel in Mombasa, Kenya, "demonstrate the continued willingness of Al Qaeda to strike at peaceful, innocent civilians."
He also said the global terror network could even try to mount a chemical, biological or radiological attack.
Ridge said that local and state law enforcement agencies, the nation's governors, many mayors and Congress had been informed of the change in the alert status.
Ridge also plans to talk to congressional leaders and to several dozen business leaders who control critical infrastructure, which could include electric power grids, dams or nuclear plants.
"We're asking all these leaders to increase their security and vigilance wherever necessary," he said.
The public will likely see some changes, such as delays at some facilities and events, and increased security at some buildings. Other precautions, however, will be secret and go largely unnoticed by the general public.
The alert level has been at yellow, or "elevated," which is the middle of a five-point scale of risk developed after the Sept. 11, 2001 attacks. It was last raised to orange, the second level, on Sept. 10, the day before the first anniversary of the Sept. 11 attacks, and it stayed at that level for two weeks.
The highest alert level is red, a "severe" risk of terrorist attack.
The State Department on Thursday issued a "reminder" to Americans at home and abroad to be on alert for terrorist activity.
Officials are increasingly worried that Al Qaeda and other terrorist groups might try to use chemical, biological or radiological weapons such as a "dirty bomb" that spews radiation into the atmosphere over a relatively confined area. There is no evidence, they say, that Al Qaeda has acquired nuclear weapons, but there is ample proof that it was working with a variety of harmful substances.
There is also concern that individual Al Qaeda members or sympathizers could attempt small-scale attacks, such as a shooting or homicide bombing.
Although Al Qaeda has been largely driven from its former refuge in Afghanistan, the FBI cites the October nightclub bombing in Bali, Indonesia, that killed nearly 200 and November attacks on an Israeli resort and airliner in Kenya as evidence the network can still inflict great damage.
As in the past, officials said they had no information regarding specific terrorist threats and no indication of a time, place or manner of any attack. The FBI, however, is preparing to tell Congress that Al Qaeda remains the greatest threat for carrying out a terror attack on U.S. soil.
The alert level was raised last September, when a high-level Al Qaeda prisoner warned that an attack was imminent on U.S. embassies in southeast Asia.
Those attacks did not take place and may have been broken up by arrests. U.S. officials say they have thwarted more than 100 terrorist plots around the world, including some planned within the United States, since the Sept. 11 attacks.
The Associated Press contributed to this report.