Al Qaeda "chatter" is intensifying. So, too, are threats of retaliation to any US-led invasion by Saddam Hussein. And Islamic groups sympathetic to Iraq's plight - like the Palestinian Hamas - are threatening to strike US interests.
That's why US officials have placed the terrorist threat index at "high risk," only the second time it's been raised to that level since 9/11. While authorities have long predicted another terrorist attack on US targets, either at home or abroad, intelligence officials and outside experts see several factors at work that make this a particularly vulnerable time:
• The "yoohoo" factor. It's well known that Osama bin Laden and his terrorist acolytes, who have been lying low, like the limelight. And with the US pushing much more, at least publicly, toward a showdown with Iraq, they could be ready to act because they're frustrated or because they think the US is more vulnerable at the moment.
Although the US has done a great deal to dismantle Al Qaeda, the directors of both the CIA and FBI have recently said the organization is as dangerous as it was prior to 9/11. "Osama [bin Laden] may be saying, 'Yoohoo, US, don't count us out,' " says Jerrold Post, a former CIA profiler.
• The "cornered" theory. If Iraqi President Hussein, the ultimate survivor, were to launch a terrorist attack, it would most likely come when he is backed into a corner. And with the inspections regime becoming more intrusive and the US moving inexorably toward war, the walls are clearly closing in.
Experts doubt Mr. Hussein would attack the American homeland. For one thing, he probably doesn't have the weapons to do so. But either he or his top lieutenants could launch attacks with weapons of mass destruction on American soldiers and other interests in the Middle East and Europe.
• General Muslim angst. More likely than a hit by Hussein, say Mr. Post and other experts, would be an increase in Hamas and Islamic jihad terrorism aimed at Israel. The already visceral and vocal reaction many Muslims have had to US policy in the Middle East will likely only increase. Indeed, Sheikh Ahmed Yassin, the spiritual leader of Hamas, released a letter Friday in which he admonished Muslims everywhere to strike "Western interests" if the US goes to war.
All this is believed to have contributed to the US moving its alert system to "orange" on Friday. The only other time it's been that high is last September, just before the attacks in Bali. Jewish sites in the US are one area that may be a target. "Recent reporting indicates an increased likelihood that Al Qaeda may attempt to attack Americans in the United States or abroad," during the Hajj, a Muslim holy period that began yesterday and ends Feb. 14, said Attorney General John Ashcroft on Friday.
Yet the question persists: How well prepared is the US for another assault? Most experts think if there is another strike, it won't be another World Trade Center-type attack, though they don't rule that out. Instead, they say it is more likely to be a "soft target." That could include hotels, apartment buildings, and tourist attractions. And intelligence officials say they are hearing all sorts of threats.
"It could be a radioactive dirty bomb," says one intelligence official. "It could be a suicide bomber, any number of things. We know terrorists are here in the US, and we know they have operations in various planning stages. We just have to be prepared."
At the newly formed Department of Homeland Security (DHS), efforts are under way to coordinate public protection and a response to any attack. "We make preparations based on each situation, each threat, and each bit of intelligence," says Brian Roehrkasse, a spokesman for DHS. "But I won't address the specifics of that at this juncture."
However, DHS Secretary Tom Ridge and Mr. Ashcroft said they'd increased security across the nation in several ways. Random searches at airports have been ramped up. Additional air marshals are flying. And there are more visible military and police patrols in the nation's major cities. The borders, ports, and infrastructure have been buttoned down.
But Juliette Kayyem, an expert on domestic preparedness at Harvard University's Kennedy School of Government, says the US is not nearly as prepared as it should be.
"There's been a lot of talk about the cost of not going in to get Hussein," Ms. Kayyem says, "but there's been no open discussion of what the realistic assumptions are about what he might do if we do go in."
Kayyem, who also is a former member of the National Commission on Terrorism, says, "the public is totally unprepared. There's been a lot of good talk, but the money hasn't gotten down to the localities for any kind of security training."
But security experts say it is nearly impossible to protect everything. Terrorists hone in on vulnerabilities, "targets least likely to be protected," says Robert Pfaltzgraff, an expert on international security at Tufts University's Fletcher School of Law and Diplomacy in Medford, Mass. "We need to take that into account in preparing a response."
At the same time, Dr. Pfaltzgraff says, "We should realize the ability of the US to retaliate and go to the source of terror, which was demonstrated by the US response to 9/11. That hasn't eliminated the danger, but it may make those who perpetrate these acts think twice."
That would apply especially to other Islamic groups, such as Hamas, Islamic Jihad, Hizbullah, and others that are on the Bush administration's list of terrorist organizations. The US knows where they are, and certainly would retaliate against them.
Pfaltzgraff also points out that Americans are much more alert now than before 9/11. And the elevated terrorist risk threat calls for more vigilance on the part of Americans. "Remember," Pfaltzgraff says, "it was alert flight attendants and passengers who subdued shoe bomber Richard Reid on that trans-Atlantic flight."