Top officials countered that the terror operation would have occurred even if the United States had been able to kill the al Qaeda leader.
Defense Secretary Donald H. Rumsfeld and Secretary of State Colin Powell, in a strong defense of pre-Sept. 11 actions that have become a major election campaign issue, told the federal commission reviewing the attacks that the plot was well under way when the Bush administration took office in January 2001.
"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."
Earlier, Secretary of State Colin Powell stressed administration efforts to fight terrorism, an implicit rebuttal to criticism in a new book by, who is expected to testify Wednesday.
Powell said that even if U.S. forces had invaded Afghanistan, killed bin Laden and neutralized al Qaeda, "I have no reason to believe that would have caused them to abort their plans."
Separately, President George W. Bush said Monday thatmore quickly before Sept. 11 "had my administration had any information that terrorists were going to attack New York City on Sept. 11."
Responding for the first time to former counterterrorism adviser Richard Clarke's pointed accusations that he ignored the threat from al Qaeda until after 9-11, the president carefully remained above the battle, reports CBS News Correspondent Bill Plante.
The testimony by Rumsfeld and Powell came against the backdrop of counterterrorism adviser Richard Clarke's claim that top Bush administration officials had ignored bin Laden and the threat of the al Qaeda terror network while focusing on Iraq's Saddam Hussein.
Powell did not mention Clarke, but said, "President Bush and his entire national security team understood that terrorism had to be among our highest priorities and it was."
Yet, not until the day before the attacks did U.S. officials settle on a strategy to overthrow the Taliban Afghan government in case a final diplomatic push failed. That strategy was expected to take three years, the commission said.
The commission report said U.S. officials, in both the Clinton and Bush administrations, feared a failed attempt on bin Laden could kill innocents and would only boost bin Laden's prestige. And the American public and Congress would have opposed any large-scale military operations before the September 2001 attacks, the report said.
In the end, it said, pursuing diplomacy over military action allowed bin Laden and other al Qaeda leaders to elude capture.
The panel investigating Sept. 11, formally the National Commission on Terrorist Attacks Upon the United States, is holding two days of hearings with top-level Bush and Clinton administration officials. The aim is to question them on their efforts to stop bin Laden in the years leading up to Sept. 11.
The commission's staff has spent months interviewing Clinton and Bush administration officials and poring over documents. Its preliminary findings, included in two statements issued Monday, will be considered by the 10-member panel, which plans to issue a final report this summer.
The staff reports found both administrations lacked the detailed intelligence needed to strike directly at bin Laden, so they fruitlessly sought a diplomatic solution to get the al Qaeda leader out of Afghanistan
Former Defense Secretary William Cohen said the Clinton administration recognized the dangers posed by al Qaeda and considered the United States to be "at war" against the terrorist organization. Three times after August 1998, U.S. officials considered using missile strikes to kill bin Laden, but each time it was decided the intelligence wasn't good enough to ensure success, he said.
Former Secretary of State Madeleine Albright told the commission that President Bill 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."
Among the staff findings:
Rumsfeld told the commission that "he did not recall any particular counterterrorism issue that engaged his attention before" the Sept. 11 attacks, other than using unmanned aircraft against bin Laden.
In a secret diplomatic mission, Saudi Arabia won a commitment from the Taliban to expel bin Laden, but Taliban leaders later reneged.
"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."
Shortly before the attacks, the Bush administration was debating how to force bin Laden out. At a Sept. 10, 2001, meeting of second-tier Cabinet officials, officials settled on a three-phase strategy. The first step called for dispatching an envoy to talk to the Taliban. If this failed, diplomatic pressure would be applied and covert funding and support for anti-Taliban fighters would be increased.
If both failed, "the deputies agreed that the United States would seek to overthrow the Taliban regime through more direct action," the report said. Deputy national security adviser Stephen Hadley said the strategy had a three-year timeframe.