The U.S. government was utterly unprepared on Sept. 11, 2001, to protect the American people from al Qaeda terrorists, who outwitted and outmaneuvered a bureaucracy that had never seriously addressed them as a threat and had never fathomed the possibility of such a calamitous assault on U.S. soil, according to a searing account of failures and missteps released yesterday.

The 567-page final report of the commission investigating the Sept. 11 attacks chronicles in exhaustive detail the sporadic and failed attempts of the CIA, the FBI and other intelligence agencies to track some of the Sept. 11 plotters and their associates. Although it stops short of blaming President Bush or former president Bill Clinton for the attacks, the document concludes that both administrations were lackluster in their efforts to combat Islamic terrorism and derides congressional oversight of the issue as "dysfunctional."

"The 9/11 Commission Report," available in paperback in bookstores nationwide, proposes a series of controversial reforms that would amount to perhaps the most dramatic restructuring of the U.S. government in half a century. The 10-member bipartisan panel recommends forming a new Cabinet-level office of national intelligence and creating a terrorism center that would not only analyze intelligence but also run its own counterterrorism operations at home and abroad. The commission wants Congress to completely change the way it governs the intelligence community as well.

In proposals that would have a major impact on virtually every American, the report advocates encoding U.S. passports with personal information -- as is now required for some foreigners entering the United States -- and recommends standardized driver's licenses nationwide. Both ideas were met with immediate criticism from civil liberties advocates.

After 20 months of interviews, hearings and other research, the commissioners concluded that the United States had not even come close to thwarting the attacks.

"Since the plotters were flexible and resourceful, we cannot know whether any single step or series of steps would have defeated them," the commission's chairman, former New Jersey governor Thomas H. Kean (R), said at a news conference in Washington. "What we can say with a good deal of confidence is that none of the measures adopted by the United States government before 9/11 disturbed or even delayed the progress of the al Qaeda plot. . . .

"The government failed to protect the American people," Kean added. "The United States government was simply not active enough in combating the terrorist threat before 9/11."

Congressional leaders have sent mixed signals in recent days about the chances of enacting the proposed reforms in an election year, but Kean and other commissioners vowed to lobby for the changes in coming months. The panel plans to assemble a "report card" in six to 12 months on the government's progress.

At a news conference with the commission's leaders yesterday, Sens. John McCain (R-Ariz.) and Joseph I. Lieberman (D-Conn.) said that after the summer break they will offer legislation that embodies most of the panel's recommendations. McCain said he will urge the congressional leadership to schedule hearings to begin after the election, in a lame-duck session, with the goal of completing congressional action next year.

Bush praised commissioners for their work and said he agreed with them "that the terrorists were able to exploit deep institutional failings in our nation's defenses that developed over more than a decade."

"The commission has suggested a number of reforms to improve our intelligence capabilities so we can better anticipate emerging threats," he said in a speech in Glenview, Ill. He said the administration will "carefully study all of their proposals," but did not take a position on the commission's major recommendations.

National security adviser Condoleezza Rice told reporters after the report was released: "I don't think it's a matter of whether there will be further intelligence reform. I think there will be further intelligence reform. It's a matter of how and precisely when, and precisely what will be done."

Democratic presidential candidate John F. Kerry, who has endorsed some reforms that are similar to those the commission advocated, told reporters in Detroit that the "report carries a very simple message for all of America about the security of all Americans: We can do better."

About three dozen relatives of Sept. 11 victims were briefed on the report in Washington just before its public release, and most praised the commission for its steadfastness and urged quick adoption of all its recommendations. A small cadre of activist Sept. 11 families had lobbied for the panel's formation and has closely followed its work.

"I was pleasantly surprised the commission did a heck of a job," said Rosemary Dillard of Alexandria, whose husband, Eddie, died in the Pentagon. "Now we'll be busier than ever making sure those in office know what they are doing." Others, however, expressed disappointment that the commission was not more specific in placing blame for missteps before Sept. 11, and that it did not judge whether the attacks could have been prevented.

Drawing from 2.5 million pages of documents, 1,200 interviews and numerous public hearings, the report by the commission, known formally as the National Commission on Terrorist Attacks Upon the United States, relies heavily on findings released by the commission's staff over the past seven months while adding significant new details about the plot and the government's efforts to grapple with terrorism.

The document, which includes 116 pages of footnotes, provides a remarkable window into the government's secretive war on terrorism and examines the internal debates that raged in the U.S. government over the past decade about the emergence of al Qaeda. The panel also weighs in on such issues as antiterrorism legislation and the status of detainees being held at Guantanamo Bay, Cuba, arguing that the government must justify its use of some of the powers granted under the USA Patriot Act and advocating adherence to the Geneva Conventions in its treatment of alleged combatants.

At the same time, the five Republicans and five Democrats on the commission clearly held back from offering conclusions on some of the most divisive political issues surrounding the attacks, in part because Kean and Hamilton had aimed from the beginning to produce a unanimous and arguably apolitical report.

The panel ducked an issue that exploded on the political stage this spring, for example, when former counterterrorism coordinator Richard A. Clarke alleged in testimony and a best-selling book that the Bush administration had been less aggressive than the Clinton administration in combating terrorism. The commission's executive summary says only that "terrorism was not the overriding national security concern for the U.S. government under either the Clinton or the pre-9/11 Bush administration."

Former senator Bob Kerrey (Neb.), a Democratic commission member, said in an interview yesterday that some issues had to be skirted or softened to avoid "a five-five report."

"It's one of the consequences you have when you're selected by political parties in the most partisan town on the planet," he said. "It's very difficult to criticize one side and not the other without appearing partisan, especially when one of them is up for reelection."

Yet through its wealth of detail and fact-finding, the report leaves clear impressions of the commission's apparent views on several of the politically volatile issues it considered. The panel finds that Iraq and al Qaeda had no "collaborative operational relationship," for example, while it outlines a much deeper alliance between the terrorist group and Iran. The report alleges that as many as 10 of the 19 Sept. 11 hijackers were able to freely pass through Iran, although there is no evidence that Tehran was aware of the plot.

The panel also said it could not determine whether the attacks could reasonably have been prevented. Yet it identifies 10 "operational opportunities" that were missed in detecting the plot, and identifies nine major vulnerabilities that enabled the attacks to move forward.

Some of the shortcomings outlined were matters of policy, such as the failure to act on recommendations for hardening cockpit doors on jetliners or the failure to include suspected terrorists on aviation no-fly lists.

Many of the vulnerabilities and missed chances outlined revolved around two of the leading Sept. 11 hijackers, Khalid Almihdhar and Nawaf Alhazmi, who evaded serious detection by the CIA and, later, the FBI, despite numerous opportunities. Although the mistakes by the CIA, in particular, have been documented previously in the case of these two hijackers, the commission report provides a definitive and damning look at the details.

From the emergence of Alhazmi and Almihdhar at an al Qaeda operations meeting in Kuala Lumpur, Malaysia, in January 2000, the CIA repeatedly lost track of the pair and failed to properly follow up on their whereabouts, the report said. And once the CIA finally placed their names on a terrorist watch list in August 2001, the two had already entered the United States and the FBI was laggard in its efforts to find them, according to the commission account.

The report also chronicles the missteps of the FBI in its handling of Zacarias Moussaoui, whose arrest in August 2001 was suspicious enough that the then-director of the CIA, George J. Tenet, was briefed. Yet senior FBI managers never received word of the case and headquarters officials wrongly believed they could not gain a warrant to search Moussaoui's belongings. The commission concluded that Moussaoui was probably being prepared as a replacement Sept. 11 pilot.

Among the many other historical topics addressed by the commission:

* The report concludes that the stated intent of the Clinton administration to kill Osama bin Laden "was never well communicated or understood within the CIA."

Clinton and his national security adviser Samuel R. "Sandy" Berger told the commission that by 1999, the president "wanted him dead." Tenet, however, testified that he believed the CIA was authorized to kill bin Laden only if force became necessary in an attempt to capture him.

A former chief of the unit pursuing bin Laden said that was a crucial difference. "We always talked about how much easier it would have been to kill him," the former unit chief said.

* Bush and Clinton, both interviewed by the commission, disagreed in their recollection of a two-hour meeting on national security and foreign policy issues in December 2000. Clinton recalls telling Bush that "by far your biggest threat is Bin Ladin and the al Qaeda" and that he regretted not capturing or killing the al Qaeda leader.

Bush told the commission "that he felt sure President Clinton had mentioned terrorism, but did not remember much being said about al Qaeda." Bush said Clinton emphasized other issues, such as North Korea and the Israeli peace process.

* In a long footnote, the 10 commissioners upbraid Attorney General John D. Ashcroft for claiming during commission testimony that a 1995 memo had laid the foundation for a legal wall between intelligence and criminal investigations that hampered counterterrorism. The memo's author, former deputy attorney general Jamie S. Gorelick, is a Democratic member of the commission.

Ashcroft's testimony "does not fairly or accurately reflect the significance of the 1995 documents" and the memo had no bearing on key decisions made in the summer of 2001 related to the Sept. 11 plot, the report said.

The panel did not draw conclusions about another dispute involving Ashcroft, who denied telling former acting FBI director Thomas J. Pickard in the summer of 2001 that he did not want to hear about terrorist threats. The panel identifies additional witnesses who support Pickard's account, but Ashcroft aides have disputed it.

* The panel sharply criticized both the Bush and Clinton administrations for failing to respond to the October 2000 attack on the USS Cole in Yemen that killed 17.

* The commission also concluded that the failed airstrikes in 1998 against bin Laden camps in Afghanistan and an alleged chemical weapons plant in Sudan may have made the Clinton administration overly wary of using military force against al Qaeda. The panel noted allegations by some Republicans that Clinton may have ordered the strikes to distract attention from the Monica S. Lewinsky scandal, echoing the plot of the 1997 movie "Wag the Dog." "The failure of the strikes, the 'wag the dog' slur, the intense partisanship of the period and the nature of the al Shifa evidence, likely had a cumulative effect on future decisions about the use of force against Bin Ladin."

Staff writers Dan Morgan, Mike Allen, Glenn Kessler, Spencer S. Hsu, Michael Powell, Susan Schmidt, Peter Slevin, Bradley Graham, Ceci Connolly and Walter Pincus contributed to this report.

The Sept. 11 commission's chairman, Thomas H. Kean, and vice chairman, Lee H. Hamilton, present their final report, which was drawn from 2.5 million pages of documents, 1,200 interviews and numerous public hearings."The government failed to protect the American people," the panel chairman, Thomas H. Kean, left, said at a news conference. With him are Vice Chairman Lee H. Hamilton, Fred F. Fielding, Bob Kerrey, John F. Lehman and Richard Ben-Veniste. The bipartisan 10-member panel began its work 20 months ago.