"I certainly think that by our actions now that we have disrupted it," said Frances Fragos Townsend, President Bush's homeland security adviser. "The question is, have we disrupted all of it or a part of it? And we're working through an investigation to uncover that," she said in a broadcast interview.
Townsend said it is not clear how much has been uncovered about a potential plot around the November presidential election. "This certainly looks like it was a piece of it," she told CBS News' Face the Nation.
A senior intelligence official told the New York Times that one of the arrested men, computer expert Mohammad Naeem Noor Khan, was in contact with al Qaeda operatives who are plotting to disrupt the fall elections.
In cooperation with U.S. intelligence agencies, authorities in Pakistan and Britain have detained suspected al Qaeda operatives, while computer files uncovered in Pakistan contained surveillance information of five financial sites in New York, Washington and Newark, N.J. The United States issued a terror alert based on that information.
Some have questioned whether the warnings were politically motivated to strengthen Bush's image as commander in chief in an election year.
British Home Secretary David Blunkett said in a statement reported by Reuters there was "a difference between alerting the public to a specific threat and alarming people unnecessarily by passing on information indiscriminately."
Newsweek reports that a "knowledgeable British source" says Bush administration officials "compromised an ongoing surveillance operation that ultimately could have uncovered more about al Qaeda operations around the world" by raising the terror threat last week and publicly revealing new intelligence they had found.
A Pakistani intelligence official told Reuters that Khan was working secretly to help investigators track down al Qaeda militants when his name appeared in U.S. newspapers as a source of the information that lead to the terror alert.
In addition to the five financial buildings, counterterrorism officials have said other sites have been mentioned as possible targets. Asked whether there have been threats against the Capitol and members of Congress, Townsend said, "Yes, in the past, and as part of this continuing threat stream."
"We may see additional U.S. targets," Townsend said. "It's hard to judge that now until we have a better sense of what we see out of Great Britain, Pakistan and this arrest over the weekend in the United Arab Emirates."
Included in information obtained on three laptop computers and 51 discs seized in a July 24 raid in Pakistan were details of how al Qaeda operatives thought of using speedboats and divers to carry out attacks in New York harbor before the November presidential election, a U.S. law enforcement official told the newsmagazine Time.
According to both Time Magazine and The New York Times, terrorists have also considered using tourist helicopters in some New York operations. As a result, reports the Times, security measures for helicopter operators and passengers are being tightened and may include scrutiny of items being taken onboard by passengers.
A senior Pakistaniin the UAE and has been handed over to Pakistani officials.
Both Townsend and Bush's national security adviser, Condoleezza Rice, praised Pakistan's efforts.
"Three years ago, Pakistan was not a fighter in the war on terrorism," Rice said in a broadcast interview. "And here you have them able to take down terrorists and to provide information, which then could be shared."
Rice defended the administration's decision to issue the terror warnings and tighten security in the three cities even though some of the surveillance intelligence on which the government acted dated from four years ago. Some have questioned whether the warnings were politically motivated to strengthen Bush's image as commander-in-chief in an election year.
"The idea that you would somehow play politics with the security of the American people - that you would not go out and warn if you have casing reports on buildings that are highly specific," Rice said. "Are you really supposed to not tell?"
Townsend and Rice said the administration is concerned that terrorists will try to disrupt the Nov. 2 election.
"The American people are going to react very badly to any attempt to disrupt our electoral process, but I think that in some of their minds, this is a possibility and we've indeed picked up discussion of trying to do something in the pre-election period," Rice said in a broadcast interview.
To act quickly on recommendations from the commission that investigated the Sept. 11 attacks, House Democratic leader Nancy Pelosi of California has urged Speaker Dennis Hastert, R-Ill., to call a special session of Congress. Hastert said House committees are working on the recommendations.
"I hope that, when we come back in September and October, we have the recommendations and we can move forward," Hastert said. Legislation to overhaul intelligence agencies could pass this year, he said.
"I think that's possible," Hastert said. "But always what I wanted to say is we don't want to knee-jerk into something with bad results."
Pelosi has called House Democrats to a meeting Tuesday with commission members. Also this week, House committees are holding hearings on the panel's recommendations, which include creating a national intelligence director.
The bipartisan commission says the director should have full budgetary authority. Bush says the director should be able to coordinate the budgets, but not necessarily have the final say on how much agencies receive or how the money is spent.
Rice said Bush wants to ensure that the intelligence director has "effective authority" over all intelligence budgets; she stopped short of saying the post would have total control.