L.A. a top concern for terror alert
'Trying to beat a ticking clock'
Los Angeles International Airport, or LAX, was the target of a thwarted terror attack in 1999.
CNN's Jeanne Meserve on what's behind the alert.
CNN's Lisa Sylvester on the strain put on local budgets.
CNN's Soledad O'Brien talks with Tom Ridge.
LOS ANGELES, California (CNN) -- The United States Tuesday ratcheted up security on land, at sea and in the air following an "orange alert" that terrorists may again be planning to attack the homeland -- possibly using weapons of mass destruction, senior officials fear.
The concerns are based on intercepted communications from people described as "terrorist supporters," the officials said.
It's not known whether al Qaeda or related terror groups have the capacity to use WMD but, one top U.S. official said, "We know they are trying real hard to get it."
In Washington, one federal law enforcement official said the greatest level of concern nationally appeared to be "in L.A. and LAX," referring to Los Angeles' airport code.
Los Angeles Mayor Jim Hahn announced a ban on curbside drop-off and pick-up of passengers by private cars at the airport until January 4. Taxis and shuttles will still be able to drive close to the terminals, he said.
The city's police chief said he's more concerned than ever about the potential for terror.
"The concern at this juncture is higher than it has been in the past," Police Chief William Bratten told CNN. "This is my third orange alert since I've been here and this one is much more significant and is being responded to in a more significant way."
He said officials were drafting a plan in the event a terrorist act occurred and the threat level were raised to the highest level, (red).
Bratten said police patrols around the perimeter of LAX have been increased because of concerns that someone could try to shoot down an airliner using a shoulder-launched missile.
He said the ports of Los Angeles and nearby Long Beach, California, could be targeted by terrorists using explosives to disrupt commerce and that security has been beefed up at both places.
In response to the alert, Los Angeles police made an arrest in an ongoing post-9/11 roundup aimed at disrupting terrorist activity.
The man arrested was charged with fraud -- not terrorism -- but likely would not have been picked up at this time were it not for the heightened terrorism concerns, LAPD sources said.
A federal law enforcement source told CNN a number of grand jury subpoenas have been issued in the Los Angeles area in the past few days as part of a "massive investigative effort" -- with a real sense, the source said, of "trying to beat a ticking clock."
Newly installed California Gov. Arnold Schwarzenegger said security has been increased across the state.
"Airports, harbors, bridges, power plants and other key areas will receive extra security," he said. "This is an elevated state of readiness to ensure the safety of all of our people in California."
The higher security alert imposed this week was prompted by intelligence information indicating a "credible" threat of terrorist attack. The biggest worry was the possibility that al Qaeda could hijack a plane from another country and use it as a weapon, similar to the 9/11 attacks.
The cities of biggest concern were Los Angeles, New York, Washington and Las Vegas, where some of the 9/11 terrorists were known to have stayed, and sources confirmed intelligence was received about San Francisco and an area in Virginia.
Missile batteries were being moved into place around Washington and "irregular air patrols" were ordered because of what one senior Pentagon official called "specific, reliable, credible" intelligence regarding a possible terror strike.
U.S. military jets patrolled major cities at random and for the first time since the September 11, 2001, attacks National Guard units were mobilized to provide high-visibility security at airports in New York City and elsewhere.
There are briefings -- sometimes several in a day -- involving various FBI field offices in key cities -- especially New York, Washington and Los Angeles -- in an effort to "coordinate the intelligence gathering," a federal source said.
Numerous people named on America's terrorist watch lists have been prevented from entering the United States, a government official said Tuesday.
The official, who would not provide specifics, said the people were turned back at various locations. Another government official said a handful of flight crew members from other countries also have been stopped in recent days.
A planned New Year's Eve concert scheduled to be held in front of the new Walt Disney concert hall in downtown Los Angeles was canceled Tuesday due to security terms, the promoter told CNN.
The United States has been working with airlines and governments of other countries in an attempt to improve their security, especially after Sunday's move by the Department of Homeland Security to raise the nation's terror threat level from "elevated" (yellow) to "high" (orange).
In addition, a senior State Department official said Tuesday the U.S. government has received intelligence that al Qaeda is planning attacks against U.S. interests in Saudi Arabia, Bahrain, Yemen and Kenya. The official said the United States is getting "good cooperation throughout the [Persian] Gulf" in terms of providing extra security to U.S. facilities. (Full story)
$1 billion a week in security
The threat level has been raised to high several times since the attacks on September 11, 2001, but officials at all levels said the threat this time around seems more serious than prior threats.
Some homeland security officials predicted the increased security could last into February, at a cost of about $1 billion per week -- much of it in increased overtime costs for law enforcement personnel.
Thirty members of the Alabama National Guard were deployed Tuesday to assist with security in four major Alabama airports in response to the heightened terrorism threat alert.
New York Gov. George Pataki told reporters that he signed an executive order to allow state troopers from New York, Connecticut and New Jersey to ride and monitor commuter trains.
In addition, he said, "We've increased patrols along the Canadian borders and ... are working to make sure everything from airports to bridges, tunnels and other mass transit facilities have heightened security."
But Pataki urged visitors and residents to get out and enjoy the season. "Go to the restaurants, see the shows; there's no more exciting or better place to be."
CNN's Jeanne Meserve and Kathleen Koch contributed to this report.