"These intelligence reports have provided a level of detail that is very specific," he said. "The quality of this intelligence, based on multiple reporting streams in multiple locations, is rarely seen, and it is alarming, in both the amount and specificity of the information."
As a result, Ridge's office raised the threat level to its second-highest position for the headquarters of the World Bank and the International Monetary Fund in Washington, the New York Stock Exchange, and key private financial institutions in the New York area.
Yesterday, several news organizations, including "The New York Times" and "The Washington Post," published stories about the source of the intelligence leading to the elevated security. They referred to two raids in Pakistan over the past two weeks that yielded the information.
Other accounts spoke of daily meetings of senior officials of the Central Intelligence Agency, the Federal Bureau of Investigation, and other intelligence-gathering organizations. They say it was at these meetings -- once forbidden, now routine -- that the information was put into focus, forming the basis for the heightened alert.
While a raised danger level can cause public alarm, such stories in the media also may serve to reassure Americans that their government is taking appropriate action to protect them. But what is it doing to its ability to gather intelligence?
Kenneth Allard -- a retired U.S. Army colonel who served as an intelligence officer -- says the first rule of spying is to publicize it as little possible. He tells RFE/RL that one may be tempted to leak information to calm a jittery populace. But he says it is important to weigh that against giving away operational secrets.
And, Allard says, it may be some time before the government can know that such a proper balance has been reached: "Information -- and the information advantage -- is very perishable. It may very well have been the fact that they [the Americans] thought they had specific enough intelligence that by blowing [revealing] the source a little bit, they might be able to deter whatever was going to go down [whatever the conspirators were planning]. And you don't know really whether that worked until [laughs] at least six months from now."
At the same time, he says, the deterrent factor alone may be valuable enough that publicizing these sources may be worthwhile: "If it [a plot] is delayed, if it is confused, if it has to be reorganized, it may very well be that you gain the advantage of time. In that time you may turn [get cooperation from] a second source, you may get a lucky arrest, a lot of things can happen. So it's not a bad strategy."
Simon Serfaty is a specialist in international security issues at the Center for Strategic and International Studies, a policy research center in Washington. He agrees that U.S. officials probably were careful in weighing the advantages and disadvantages of publicizing the information.
But Serfaty tells RFE/RL that the administration of President George W. Bush is probably quicker to release such information today than it would have been before the attacks of 11 September 2001. The reason, he says -- to some extent -- is self-interest: "The debate over September 11 is very much based, at least in part, on the idea that 'You knew much more than you shared with us. Why didn't you act upon what you knew?' And by sharing the information more widely now -- even information that is not possibly entirely credible -- the policy-makers are protecting themselves. It's a kind of insurance policy."
Serfaty says publicizing this intelligence-gathering speaks of more than the motives of U.S. officials. What is more disturbing, he says, is that it says much about Pakistan, where the intelligence was gathered.
While Pakistani President Pervez Musharraf may be at least nominally Bush's ally, Serfaty says, many of his people are more closely aligned with Al-Qaeda and the Taliban -- and allowed those groups to operate in neighboring Afghanistan.
As a result, Serfaty says, Musharraf is forced to perform a political balancing act: "Musharraf has two constituencies with contradictory needs. One is here in the West. He has asserted himself as a close ally of Bush, and that is very important. On the other hand, he has a domestic constituency which is, in fact, fairly pro-Islamist. And so he's catering to both, and to that extent he is playing a double game."
Serfaty says the best intelligence can, perhaps, deter attacks by groups like Al-Qaeda. But intelligence alone cannot rid Pakistan of people who gladly give the group a place to plan them.