In stark contrast to last year's holiday season, when the nation was under heightened alert, counterterrorism officials say there is precious little intelligence "chatter" being picked up about any new plot this year.

U.S. and foreign intelligence and law enforcement services report a continuing stream of vague, lower-level threats from Al Qaeda (search) and other Islamic extremist groups against American interests at home and abroad. But officials say nothing specific and credible has emerged in recent months that would require the government to raise the risk level above yellow, or "elevated," the midpoint on the five-level threat scale.

But the threat of another terrorist attack on the United States still exists.

"It's a little bit like a duck on a pond. You've got a lot going on under the surface but you don't have any big waves," FBI counterterrorism and counterintelligence chief Gary Bald (search) said in an interview Thursday.

Just before Christmas last year, the threat level was raised to orange, or "high," and flights to the United States from Paris, London, Scotland and elsewhere were canceled over several days. The FBI, the Homeland Security Department and other agencies scrambled to check names booked on those flights for possible Al Qaeda operatives either trying to get into the United States or to target the flights themselves.

In those cases, U.S. and European officials were acting on difficult-to-obtain intelligence singling out specific flights of concern. But even then, no arrests were announced and it was unclear if any plots were thwarted.

Nothing like that has surfaced this year, despite a general concern that terrorists might try to disrupt the holidays or take advantage of hectic travel times to mount an attack.

"We have no information about specific plots as we enter the holiday season," Homeland Security Department spokesman Brian Roehrkasse said.

Still, officials and outside experts say the relative calm and lack of an Al Qaeda attack on the U.S. homeland since Sept. 11, 2001, should not be viewed as evidence of decisive victory over terrorists. Al Qaeda is known to plan attacks patiently and could have operatives already in the United States primed for a long-awaited signal.

"When we're in a state of high alert, that's when things are not going to happen," said Michael Greenberger, director of the University of Maryland's Center for Health and Homeland Security. "It's when we're not looking, when we're overconfident, that something will happen."

The FBI, CIA and other agencies have carefully analyzed audio and video communications from Al Qaeda leader Osama bin Laden for clues about plots or timing. Although bin Laden's most recent statement focused on attacking foreign targets in Saudi Arabia, American officials aren't letting down their guard.

"I think it would be incredibly naive for us to think that someone won't try another attack," Bald said.

With a week left in the year, the war on terrorism domestically in 2004 was most remarkable for what did not happen.

After the threat involving foreign flights abated in January, officials grew increasingly concerned about a possible plot to disrupt the U.S. elections. Nothing occurred. The terror threat level was raised for specific financial institutions in New York, New Jersey and Washington after discovery overseas of detailed — albeit mainly old — surveillance of key buildings. That threat level was lowered last month after no incidents occurred.

Looking ahead, officials are planning exceptionally heavy security for the Jan. 20 inauguration of President Bush. Security also will be tight for major college bowl games and the Feb. 6 Super Bowl in Jacksonville, Fla.

There are currently no specific, credible threats of terror plots against any of those events. Despite the post-Sept. 11 advances in intelligence gathering and information sharing, officials acknowledge the silence could simply mean that the government isn't looking in the right places.

"It's not so much what we know, but what we don't know," Bald said. "The threat could still be there but it just hasn't surfaced in intelligence channels."