If the mastermind of the Sept. 11, 2001, attacks had known that Zacarias Moussaoui, an al Qaeda operative now charged as a conspirator in the plot, had been arrested in August, he might have canceled the mission.

As it turned out, Khalid Sheik Mohammed, the main strategist behind the attacks, did not find out until after Sept. 11 that Moussaoui was jailed in Minnesota on immigration charges.

That revelation, from a U.S. interrogation of one of Mohammed's top deputies, Ramzi Binalshibh, is among many new details about the planning and execution of the attacks contained in the 567-page report of the commission investigating the attacks and the government's response, which was released yesterday.

Rich in specifics, the report draws on intelligence reports not previously made public, including information drawn from CIA interrogations of al Qaeda operatives that reveal new information on the plans, motives and mind-set of the terrorists involved in the attacks, as well as others at the organization's highest levels.

The commission members believe Moussaoui was to have been among the Sept. 11 hijackers, although Binalshibh has called him a poor candidate who was needed only to fill out a shaky roster. Mohammed has told interrogators that Moussaoui was going to be part of a second wave of attacks, the report said.

The commission report provides similar glimpses of other terrorists associated with the attacks, including Mohammed, who is referred to in the report as "KSM," and who promoted the idea of using the jetliners as missiles.

Mohammed originally conceived of crashing nine airliners while he would hijack a 10th himself, killing the male passengers and landing to give a speech "excoriating" repressive Arab governments and U.S. support for Israel.

"Beyond KSM's rationalizations about targeting the U.S. economy, this vision gives a better glimpse of its true ambitions. This is theater, a spectacle of destruction with KSM as the self-cast star -- the superterrorist," the report said.

Mohammed, the report found, is not the only terrorist leader with an outsize ego and a powerful blood lust.

Abd al-Rahim al-Nashiri, who became head of al Qaeda operations on the Arabian peninsula, was "so extreme in his ferocity in waging jihad" that he would commit a terrorist act inside the holiest mosque in Mecca if he thought there were a need, according to interviews with captured terrorists, the report quoted. Nashiri, who reported directly to bin Laden, orchestrated the 2000 bombing of the USS Cole in Yemen.

Despite the attention bin Laden has received from U.S. officials, the report found that not all those working with him have accorded him undivided devotion.

Nashiri was asked to swear loyalty to bin Laden but "found the notion distasteful and refused," the report said. He was not alone: Mohammed also refused, as did Hambali, the leader of Southeast Asia's Jemaah Islamiah terrorist network who accepted bin Laden's offer in 1998 to form an alliance "in waging war against Christians and Jews."

In addition to providing new insights into some of the plotters, the report traced the evolution of the planning for the Sept. 11 attacks.

Mohammed and his nephew, Ramzi Yousef, began talking about plots to hijack U.S. airliners and crash them into buildings after the 1993 World Trade Center bombing -- for which Yousef was later convicted. Bin Laden signed on in concept in the spring of 1999.

The report reveals that the target bin Laden was most interested in hitting was the White House, even though hijack leader Mohamed Atta thought it was too difficult and preferred the Capitol.

At a meeting in Spain in July 2001, Binalshibh told Atta that bin Laden wanted the attacks "carried out as soon as possible because he was worried about having so many operatives in the United States." In early August, Atta communicated to Binalshibh that the attacks would be launched in the first week of September, when Congress reconvened.

Atta said he and Marwan Al-Shehhi would pilot airliners into the World Trade Center, and crash them on the streets of New York if they could not hit the towers. Atta had considered "targeting a nuclear facility he had seen during familiarization flights near New York," but others in the hijack plot feared they would be shot down in restricted airspace.

The commission report said that some aspects of the plot remain a mystery. For instance, two of the hijackers who have received the most attention, Nawaf Alhazmi and Khalid Almihdhar, had no English skills or exposure to life in the West, unlike the others. They arrived in San Diego in 2000 and authorities have speculated about who there may have helped them.

The report said Mohammed "denies that al Qaeda had any agents in Southern California. We do not credit this denial."

Research editor Margot Williams contributed to this report.

A hijacked airliner heads into the second World Trade Center tower on Sept. 11, 2001.Khalid Sheik Mohammed didn't know Moussaoui was in jail.Zacarias Moussaoui was to be a hijacker, report says.