"What was the cause of the breakdown in our national security? What were the reasons? I would like to know," said Sally Regenhard, whose son, Christian, was one of the firefighters killed at the World Trade Center.
Reganhard confronted Deputy Secretary of State Richard Armitage after he testified the federal government knew last summer that Osama bin Laden and Al Qaeda posed a significant threat.
"It was good enough for us to take several steps. We issued between January and September, nine separate warnings," said Armitage, adding that he hoped those warnings may have saved lives.
Armitage also said intelligence has improved, but isn't failsafe.
"So I guess another way of saying that is your administration and successive administrations have to be right every time, every single time. The terrorists only have to be right once," Armitage told Congress.
On Thursday, the joint hearing of the House and Senate Intelligence Committees was focusing on how presidents have used intelligence information. On the witness list besides Armitage were Deputy Defense Secretary Paul Wolfowitz and three former national security advisers: Brent Scowcroft, Anthony Lake and Sandy Berger.
House and Senate investigators have revealed as part of their investigation into the Sept. 11 attacks that intelligence agencies had many more warnings of possible terrorist attacks than were previously disclosed in public. Some involved targets on U.S. soil. At least a dozen warnings going back to the mid-1990s suggested airplanes could be used as weapons.
"Given the events and signals of the preceding decade, the intelligence community could have and in my judgment should have anticipated an attack on U.S. soil on the scale of 9/11," said Sen. Jay Rockefeller, D-W.Va.
Sen. Bob Graham, D-Fla., chairman of the Senate Intelligence Committees, said lawmakers want to see how the government responded to the growing threat of terrorism.
Graham told reporters that the national security councils of years past "prayed at the throne of the status quo" and failed to imagine that their intercepts pointed to Sept. 11.
He said witnesses will discuss how they assessed the terrorist threat, including the emergence of al Qaeda, which Graham said "went from a nonexistent organization ... to our No. 1 national security threat."
Lawmakers also want to see how information flowed through the government and how agencies were prepared to deal with the threat of terrorism.
Eleanor Hill, staff director for the committees' investigation into the attacks, told lawmakers Wednesday the reports were generally vague and uncorroborated. None specifically predicted the Sept. 11 attacks.
But collectively, the reports "reiterated a consistent and critically important theme: Osama bin Laden's intent to launch terrorist attacks inside the United States," Hill said at the committees' first public hearing on the attacks.
Despite that, authorities did not alert the public and did little to "harden the homeland" against an assault, she said. Agencies believed any attack was more likely to take place overseas.
Pressed by Rep. Ray Lahood, R-Ill., about whether agencies had enough information to have prevented the attacks, Hill said it was possible, but there were no guarantees.
There are too many questions, she said. Could the plot have been uncovered? What would happen if they had identified some of the hijackers? What if they were able to listen in their conversations?
"It's one 'if' after another," Hill said.
Wednesday, Kristin Breitweiser - whose husband, Ron, died at Ground Zero - told lawmakers that she questions whether the government took the precautions it should have before the attack.
"It is time to look back and investigate our failures as a nation," said
Breitweiser, who's been lobbying Congress for months as a member of the Sept. 11 Advocates, a relatives' support group.
Breitweiser and many other victims' relatives want an independent commission to investigate what went wrong.
"My husband was murdered - you know, his death certificate says 'homicide.' Sadly I don't want anyone else in America to walk in my shoes, which is why I come down here to continue to fight for this," said Breitweiser.
She showed the panel a gold ring that belonged to her husband, Ron. It was scratched around the edge but was otherwise perfectly round when it was found in the rubble of the World Trade Center. It's virtually the only trace of her husband that was ever found and she swore to wear it forever.
And there is growing support in Congress for an independent commission.
Sen. Robert Torricelli, D-New Jersey says, "Not one person has been relieved, reassigned or held accountable should be a source of outrage for every American."
Other relatives of 9/11 victims, many dressed in black, wept as lawmakers disclosed there had been warnings that planes might be used to bomb buildings.
Steven Push - of Sept. 11th Homeland Security Alliance, and whose wife was killed on the plane that hit the Pentagon - told Congress Wednesday that it's clear the intelligence community wasn't doing its job.
"Our loved ones paid the ultimate price for the worst American intelligence failure since Pearl Harbor," he said.
Hill's report also noted that during the Clinton administration in August 1999, the intelligence community obtained information indicating that bin Laden had decided to "target" then-Secretary of State Madeleine Albright, then-Defense Secretary William Cohen and CIA Director George Tenet.
The intelligence community interpreted "target" to mean "assassinate," the report said.
Details of intelligence about terrorist use of airplanes could embarrass the White House. Sen. Carl Levin, D-Mich., noted that national security adviser Condoleezza Rice had said this spring that nobody could have predicted that terrorists "would try to use an airplane as a missile."
Levin said despite her comments, the use of a plane as a terrorist weapon was not novel, "but rather a method of attack the intelligence community knew terrorists has considered as early as the mid-1990s."
The House and Senate committees have been meeting behind closed doors since June to examine intelligence failures leading up to the attacks and recommend changes.