TERROR THREATS Several plots are possible, U.S. says

Officials are also aware of reference to coordinated attacks like Sept. 11.
COMBINED DISPATCHES
WASHINGTON -- Al-Qaida operatives may be plotting several unrelated attacks in the United States, targeting not only major cities but also remote bulwarks of the "critical infrastructure" in an effort to cause mass casualties and major economic damage throughout the nation, according to U.S. officials.
Senior U.S. counterterrorism officials said they have been unable to nail down specifics about a time or place for any potential attacks, despite a mad scramble to do so since receiving an alarming cache of corroborated intelligence beginning Thursday and Friday .
But the officials say the intelligence they have received -- much of it from intercepted communications among known terrorist operatives overseas -- clearly refers to at least one series of coordinated, simultaneous strikes, like Sept. 11, as well as isolated plots of varying degrees of sophistication.
"We're concerned that there could potentially be many separate plots," said one U.S. official with knowledge of the recent intelligence. "It's hard to establish a certain theme to all of this because we are getting such a massive volume of reporting."
That official and others stressed that although much of the intelligence about a coordinated attack has been corroborated, references to other unrelated plots were in many cases based on far less reliable or fewer sources.
Areas cited
Much of the recent intelligence makes broad references to large urban areas, including New York, Washington, Los Angeles and Las Vegas. Other pieces of intelligence cite such obscure locales as Rappahannock, a rural Virginia county with several government facilities, said several senior U.S. officials.
U.S. officials said today they also have received information from a credible source about an Al-Qaida threat against oil interests in Alaska, which they have not fully corroborated. Still, officials were treating the information seriously and have taken extra security precautions.
A Coast Guard spokesman, Roger Wetherell, said that air and water patrols have been stepped up around the Port of Valdez, where tankers depart carrying Prudhoe Bay oil to the lower 48 states, and that vessel boardings will increase.
According to data received as recently as Monday, officials remain primarily concerned about Al-Qaida operatives plotting to hijack passenger and cargo planes and fly them into U.S. targets, as Homeland Security Secretary Tom Ridge said Sunday in announcing the decision to elevate the terror threat level one notch, from elevated, or yellow, to high, or orange.
They cite a large amount of corroborated and specific intelligence that refers to efforts to hijack planes not only outside the United States, where security is not as tight, but also at domestic airports by using new and improved techniques that terrorist operatives believe could thwart the nation's vast new homeland security apparatus.
But the FBI, the CIA and other authorities have also picked up intelligence about efforts to blow up chemical and hazardous materials facilities, nuclear power plants, dams, power grids, ports and airports, several U.S. officials said.
Difficult to pinpoint
One senior federal law enforcement official said the FBI and other authorities are alarmed and frustrated because the intelligence varies so widely according to potential targets and methods of attack, as well as by its degree of specificity and corroboration. Of particular concern, he said, are vague references to coming attacks on "major metropolitan areas and events that we're looking at ... bowl games, New Year's events, that kind of thing."
"There is no one specific threat here. There is no place or time to tie to this," said the senior federal law enforcement official. "So we have to take all this information and do analysis."
Meanwhile, already tight security has been fortified at transportation and energy facilities nationwide.
Bomb-sniffing canine units were added at Cincinnati/Northern Kentucky International Airport, maritime patrols were augmented near power plants that border Lake Erie, and more officers than usual were activated along the U.S.-Canadian border.
Similar defenses have been increased around key bridges, tunnels, seaports and landmarks, as well as chemical facilities and other places that may be vulnerable to attack.
Wide array of defenses
"There's going to be a menu of visible and invisible measures that are implemented," said Brian Jenkins, research associate at the Mineta Transportation Institute at San Jose State University and a special adviser to the Rand Corp., a California think tank.
Among the covert steps likely taken, Jenkins said, are an increase in the number of air marshals, particularly on flights arriving from overseas, undercover surveillance around airports and more frequent air patrols near major cities.
The Transportation Security Administration, the federal agency charged with protecting air travelers, would not discuss its planning at a detailed level, other than to confirm that vehicle inspections and parking restrictions have increased at airports and that Coast Guard patrols have been added near airports bordering oceans and lakes.
"We're putting all hands on deck," TSA spokesman Darrin Kayser said, adding that parking restrictions may require travelers to park a little farther away than they might normally.
The Nuclear Energy Institute, which represents the owners of more than 100 reactors in 31 states, said the power industry is coordinating with law enforcement and intelligence agencies and has 7,000 of its own patrolmen at the ready.
"Really, it's a paramilitary security force," said Steve Kerekes, a spokesman for the group.
The Coast Guard, meanwhile, cautioned boaters to avoid off-limits areas near power plants and to keep their eyes peeled for suspicious activity.
Amtrak said that police officers are randomly riding and inspecting trains and that patrols have been beefed up inside stations and along platforms. Some baggage is also being checked, a spokesman said.
The Air Transport Association, which represents the country's major airlines, has urged travelers to arrive two hours before domestic or international flights and to check all bags in order to expedite the screening process.