The report that so bluntly contradicts the Bush administration's claims about Saddam Hussein's links to al-Qa'ida's 9/11 attacks fills in many of the details of the plot to target American cities - detailing a blueprint that was planned to the smallest detail and which yet was still riven by differences of opinion.
The original plan, said the report, was initially conceived by "veteran jihadist" Khalid Sheikh Mohammed (KSM), a Kuwaiti from the Baluchistan region of Pakistan, who attended college in the US and then went to Afghanistan to join the fight to oust the Soviet Red Army. He was first detected by the authorities as a result of his nephew, Ramzi Yousef, who masterminded the 1993 attack on the World Trade Centre.
A year later Mr Mohammed joined Yousef in the Philippines for what would become known as the "Bojinka operation", a plot to blow up 12 US aircraft above the Pacific ocean over two days. That plot unravelled when the authorities found Yousef's bomb-making equipment. He was captured and taken to the US for trial and conviction but KSM escaped.
The report said that KSM returned to Afghanistan where he met Osama bin Laden and outlined his plan to attack the US.
KSM outlined to Bin Laden a plot to attack up to 10 US cities simultaneously. The plan was an enlarged version of the eventual attack, targeting other high-profile targets symbolic of the US and, apparently, America's support for Israel.
Following the attacks on the US embassies in Africa in 1998, Bin Laden gave his backing to KSM's plan. KSM was summoned to Afghanistan in 1999 and he was provided with four potential suicide operatives.
These men, two Saudis and two Yemenis, were sent on a training course at the Mes Aynak camp in Afghanistan, where they learned basic English, use of the internet and how to make travel reservations.
At the same time, a group of Western-educated Islamists headed by Mohamed Atta, were making their way from Hamburg to Afghanistan. They were quickly pointed towards KSM.
The report found that the attacks cost as little as $400,000. The hijackers spent around $270,000 of this in the US on travel, flight training, accommodation and living expenses. The Hamburg operatives received no funding before the end of 1999, suggesting they were financing themselves.
The hijackers received money through a variety of means, including wire transfers from al-Qa'ida operatives in Dubai. "No credible evidence exists that the operatives received substantial funding from anyone in the US," said the report.
"To date the US government has not been able to determine the origin of the money used for the 9/11 attacks. Compelling evidence traces the bulk of the funds back to KSM but where KSM obtained the money remains unknown at this time. Ultimately the question is of little practical significance. Al-Qa'ida had many avenues of funding and a pre 9/11 budget estimated at $30m."
The report noted that a number of potential hijackers were readied by al-Qa'ida but that they were forced to drop out because of problems such as obtaining visas. "According to KSM, al-Qa'idas intended to use 25 or 26 hijackers for the plot. As late as the summer of 2001, KSM wanted to send as many operatives as possible to the US in order to increase the chances for success, contemplating as many as seven hijackers per flight. We have identified at least nine candidate hijackers slated to be part of the 9/11 plot."
The report said that KSM had told investigators that as the 9/11 attacks neared, differences of opinion broke out among the al-Qa'ida leadership.
"Word started to spread that an attack against the US was imminent ... Moreover that summer Bin Laden made several remarks hinting at an upcoming attack, which spawned rumours throughout the jihadist community worldwide."
Many of the al-Qa'ida leadership urged that the attacks be called off. Bin Laden wanted to proceed. "Although he faced opposition from many of his most senior advisers, Bin Laden overruled their objections and the attacks went forward."