To hear Khalid Sheik Mohammed tell it, the Sept. 11, 2001, attacks were nothing compared with what he had in mind.

The original plan, which Mohammed says he presented to al Qaeda leader Osama bin Laden in 1998 or 1999, called for hijacking 10 jetliners on both coasts of the United States and crashing nine of them. The kicker would have been the final plane, which he would commandeer personally. After killing all the men on board, Mohammed would alert the media and deliver a speech excoriating the U.S. government for its support of Israel and repressive Arab regimes.

According to the new report from the Sept. 11 commission, the idea is classic KSM -- as Mohammed is referred to in U.S. intelligence reports -- mixing grim nihilism with a flair for the dramatic and always putting Mohammed at the center of things.

Mohammed's original vision of Sept. 11 provides "a glimpse of his true ambitions," the commission says. "This is theater, a spectacle of destruction with KSM as the self-cast star -- the superterrorist."

Mohammed, the architect of the Sept. 11 attacks, has been in U.S. custody at an undisclosed location since March 2003, when he was captured in a safe house in Pakistan. The commission's report, which was released last week, reveals rafts of information gleaned from the classified interrogations of Mohammed for the first time and relies heavily on the interviews in its examination of how the attacks were carried out.

The report portrays Mohammed, now 39, as a flamboyant and zealous operative who was continually hatching grandiose plans for terrorist attacks, even as bin Laden and other senior al Qaeda leaders urged him to stay focused on the Sept. 11 plot. The document also acknowledges doubts about Mohammad's credibility and reveals that he viewed himself as an independent contractor beholden to no one -- including bin Laden.

"No one exemplifies the model of the terrorist entrepreneur more clearly than Khalid Sheikh Mohammed," the commission wrote. "Highly educated and equally comfortable in a government office or a terrorist safe house, KSM applied his imagination, technical aptitude and managerial skills to hatching and planning an extraordinary array of terrorist schemes. These ideas included conventional car bombing, political assassination, aircraft bombing, hijacking, reservoir poisoning and, ultimately, the use of aircraft as missiles guided by suicide operatives."

Mohammed's radicalism began early, when he joined the Muslim Brotherhood at age 16. Like his nephew Ramzi Yousef, who would go on to orchestrate the 1993 World Trade Center bombing, Mohammed grew up in Kuwait but traces his lineage to Baluchistan, an area straddling the Iran-Pakistan border. As a teenager, he became "enamored of violent jihad at youth camps in the desert," the commission report says.

His first encounter with the country he would later attack with such fury came in 1983, when he enrolled at Chowan College, a small Baptist school in Murfreesboro, N.C., before transferring to North Carolina Agricultural and Technical State University. In what could be considered his first terrorist plot, Mohammed says he considered assassinating Rabbi Meir Kahane when he lectured in Greensboro, N.C., in the mid-1980s. The commission says that the claim "may be mere bravado" and that Mohammed exhibited few outward signs of radicalism in North Carolina.

But after earning a degree in mechanical engineering in 1986, Mohammed immediately journeyed to Afghanistan to join the mujaheddin fighting the Soviet occupation there. Over the next seven years, he wandered from one position to the next, and in 1992 he fought with mujaheddin in Bosnia. He then moved his family to Qatar to work as a project engineer with that country's utility ministry.

Throughout this period, Mohammed was always close to the network of radical Islamists who had fought the Soviets, but he clearly was a minor player, according to the commission account. That would soon change.

On Feb. 26, 1993, a massive explosion ripped through the parking garage beneath the World Trade Center, killing six but failing to topple the towers as the bombers had hoped. The investigation of the attack led U.S. investigators for the first time to Mohammed, who had wired $660 to one of the conspirators the year before. The probe also revealed the plot organizer as Yousef, Mohammed's nephew, who was just three years younger than his uncle.

Yousef's infamy appealed to Mohammed. "Yousef's instant notoriety as the mastermind of the 1993 World Trade Center bombing inspired KSM to become involved in planning attacks against the United States," the Sept. 11 panel found.

Within a year, he and Yousef, a fugitive, went to the Philippines to work on a plot that would serve as the inspiration for the Sept. 11 attacks. "Project Bojinka" called for the bombing of a dozen U.S. jetliners over the Pacific over two days. Mohammed and his nephew began assembling chemicals, timers and other materials while also finding time to consider an assassination attempt on President Bill Clinton.

Yousef was captured in 1995. His uncle, on the lam from U.S. authorities, would settle in Afghanistan and turn his attention to even bigger plans.

The first meeting between Mohammed and bin Laden came in 1996 at Tora Bora, the refuge in the mountains of Afghanistan where bin Laden would elude U.S. military forces after the Sept. 11 attacks. The two had known each other from their days as Afghan mujaheddin, but, the report says, "they did not yet enjoy an especially close working relationship." The report says Mohammed "has acknowledged that Bin Ladin likely agreed to meet with him because of the renown of his nephew, Yousef."

Mohammed presented bin Laden and one of his senior lieutenants, Muhammad Atef, with a virtual menu of terrorist plots, including the Philippines jetliner scheme, a plan to bomb U.S.-bound cargo ships and a proposal "for an operation that would involve training pilots who would crash planes into buildings in the United States," the report says. This idea was the seed for the Sept. 11 attacks.

Bin Laden made no commitments but asked Mohammed to join al Qaeda. Mohammed declined. Even after joining al Qaeda several years later, "KSM states he refused to swear a formal oath of allegiance to Bin Ladin, thereby retaining a last vestige of his cherished autonomy," the report says.

Mohammed also claims that he would have worked with any terrorist group, not just al Qaeda, and that he would have gone forward with the Sept. 11 attacks even if bin Laden had canceled them.

"KSM presents himself as an entrepreneur seeking venture capital and people," the commission report says. "He simply wanted al Qaeda to supply the money and operatives needed for the attack while retaining his independence."

Mohammed began recruiting hijackers and making other preparations for the attacks in early 1999. He collected aviation magazines; information on U.S. flight schools; telephone directories for San Diego and Long Beach, Calif.; flight simulator software; and other materials. He also bought Hollywood movies depicting hijackings -- but edited the films to cover up female characters before screening them for al Qaeda trainees.

Over the next two years, Mohammed arranged travel, financing and communications as the Sept. 11 hijacking teams, headed by Mohamed Atta, came together in the United States. Although the panel concludes that bin Laden and Atef -- who was later killed by U.S. forces in Afghanistan -- were deeply involved in choosing hijackers and other major decisions, Mohammed was in charge of making sure the attacks happened and mediated conflicts among the hijackers.

In U.S. interrogations, Mohammed has claimed that it was he and his colleagues who pushed a reluctant bin Laden to attack the United States; the commission disagreed, saying Mohammed was "probably inflating his own role."

Mohammed also plays down the importance of Atef and other militants allied with al Qaeda and other terrorist groups, the report says. He claims that Sept. 11 hijacker Khalid Almihdhar quit commando training after a week because it was too rigorous, but other al Qaeda detainees say he completed the course. As it happens, Mohammed did not get along with Almihdhar and would have fired him if bin Laden had not intervened.

Abu Zubaida, another senior al Qaeda official now in U.S. custody, maintains that Mohammed's original plan for Sept. 11 was more humble and that it was bin Laden who urged him to expand it. "Why do you use an ax when you can use a bulldozer?" Abu Zubaida quotes bin Laden as saying. Some high-level al Qaeda detainees also portray Mohammed as an opportunist, although he was popular with the al Qaeda rank-and-file.

Throughout this period, U.S. officials had no inkling of Mohammed's importance as an al Qaeda leader and did not conclude until well after the hijackings that he was the mastermind. Mohammed is also suspected of killing kidnapped Wall Street Journal reporter Daniel Pearl in January 2002.

Even after the 2001 attacks, which killed 3,000 and ranked as the deadliest terrorist assaults on U.S. soil, Mohammed portrayed himself as still unsatisfied. In an interview with the al-Jazeera satellite channel after Sept. 11, he claimed that an al Qaeda reconnaissance committee had identified 30 potential targets in the United States.

But, according to the commission report, "KSM has admitted that his statement . . . was a lie designed to inflate the perceived scale of the 9/11 operation."

Khalid Sheik Mohammed, who plotted the Sept. 11 attacks, has been in U.S. custody since 2003.