"Nobody has clean hands in this one," said the commission's chairman, former New Jersey Gov. Thomas Kean, a Republican, referring to the Bush and Clinton administrations. "It was a failure of individuals. The question now is whether or not we learned from our mistakes."
Richard Clarke, the former counterterrorism director under Presidents Clinton and Bush,
But asked if the Bush team could have done anything to prevent Sept. 11 from happening, Clarke answered, "No." Addressing victim's families, he apologized.
"Your government failed you, those entrusted with protecting you failed you and I failed you. We tried hard, but that doesn't matter because we failed," he said.
Clarke closed two extraordinary days of testimony featuring Secretary of State Colin Powell, his predecessor Madeleine Albright, Secretary of Defense Donald Rumsfeld, his Clinton counterpart William Cohen, CIA director George Tenet — who has served until Messrs. Clinton and Bush — and Clinton national security adviser Sandy Berger.
Many of the questions they faced concerned problems revealed in a series of preliminary commission reports.
A report released Tuesday said the Clinton and Bush administrations' failure to pursue military action against al Qaeda operatives allowed the Sept. 11 terrorists to elude capture despite warning signs years before the attacks.
The report said the U.S. government had determined bin Laden was a key terrorist financier as early as 1995, but that efforts to expel him from Sudan stalled after Clinton officials determined he couldn't be brought to the United States without an indictment.
The Saudis got a commitment from the Taliban to expel bin Laden, but the Taliban reneged. Meanwhile, Pakistan resisted years of U.S. requests to pressure the Afghan rulers. Elsewhere, Sept. 11 plotter Khalid Shaikh Mohammed was located in Qatar, but disappeared before an indictment could be brought.
In conclusion, the report said "from the spring of 1997 to September 2001, the U.S. government tried to persuade the Taliban to expel bin Laden to a country where he could face justice," the report said. "The efforts employed inducements, warnings and sanctions. All these efforts failed."
Former Secretary of State Madeleine Albright told the commission that "President Clinton and his team did everything we could, everything we could think of based on the knowledge we had to protect our people and disrupt and defeat al Qaeda."
Bush officials, meanwhile, failed to act immediately on increasing intelligence chatter and urgent warnings in early 2001 by Clarke to take out al Qaeda targets, the commission report said.
The Bush administration did not settle on a strategy to, if necessary, overthrow the Taliban Afghan government until Sept. 10, 2001. That strategy was expected to take three years, the commission said.
A report Wednesday said CIA officials, including Tenet, believed the agency lacked the authority to kill bin Laden unless his death resulted from a capture. But they never discussed this with Berger or other Clinton administration officials, who believed the CIA had the OK to kill bin Laden.
The report also said the CIA had depended too much on unreliable indigenous groups in Afghanistan, where the al Qaeda leader was running training camps under the protection of the Taliban rulers in Kabul.
Officials from both administrations largely agreed on the obstacles they faced in pursuing bin Laden. They lacked intelligence on bin Laden's whereabouts that was specific and reliable enough to launch a missile attack. They said an American invasion of Afghanistan wasn't a serious option because it would have been strongly opposed by the American public and Congress.
But Rumsfeld, Powell and Tenet all expressed doubts that the attacks could have been prevented if the Bush administration had captured or killed bin Laden.
"Killing bin Laden would not have removed al Qaeda's sanctuary in Afghanistan," Rumsfeld said. "Moreover, the sleeper cells that flew the aircraft into the World Trade towers and the Pentagon were already in the United States months before the attack."
Kean said commissioners "have experienced considerable frustration these past two days. We keep wrestling with the question: What could have been done and what should have been done at some stage or other over the past eight years to prevent 9/11?"
The commission's final report is due this summer, and is likely to become embroiled in the politics of the presidential campaign. Clarke's appearance Wednesday raised partisan tensions on a commission that prides itself on being bipartisan.
Under questioning, Clarke said the Clinton administration had "no higher priority" than combating terrorists while the Bush administration made it "an important issue but not an urgent issue" in the months before Sept. 11, 2001.
While Democrats offered praise, Republicans questioned Clarke's integrity, morality and candor. They also suggested his criticism was intended to (which is published by a company owned by Viacom, which also owns CBSNews.com) on the subject by Clarke or boost the candidacy of Mr. Bush's likely challenger in the November vote, Sen. John Kerry.
The White House
"What he is reporting … does not reflect the reality that I know to be true and I've spent a lot of time with the president. I've been in almost every one of his intel briefings," White House aide Andrew Card told CBS News. "What he alleges is not the fact."