THE two main planners of the September 11 terrorist attacks have revealed details of Osama bin Laden's close involvement in organising the atrocity, according to leaked transcripts of their interrogations.
Khalid Sheikh Mohammed and Ramzi Binalshibh, who were captured in Pakistan and are in US custody, have disclosed that bin Laden chose the pilots who flew the doomed jets and headed a committee that debated details of the attacks.
The pair have filled in many of the gaps in knowledge about how the attacks were planned, and have named previously unknown co-conspirators and other fellow al-Qaeda members, according to the transcripts obtained by a German magazine.
The men have provided a wealth of new information. They have confessed that bin Laden was intimately involved at all stages in the planning of the attacks. When, for example, Mohammed proposed attacking CIA headquarters in Langley, Virginia, with a light aircraft loaded with explosives, bin Laden replied: "Why use an axe when you can use a bulldozer?"
Mohammed also revealed that bin Laden personally selected the four pilots who took part in the attacks. When two Yemenis who had been picked could not get US visas, Mohammed Atta and Ziad Jarrahi were brought in as replacements to join Marwan al-Shehhi and Khalid al-Midhar.
Bin Laden and the committee of five other men debated all aspects of the plan as it developed. Their original idea was to organise two waves of attacks, the first using planes taking off from the US and the second in Southeast Asia.
Another early plan involved hijacking five planes on the US east coast and five on the west coast. It was abandoned because of the difficulty of co-ordinating such complex events in two time zones. Whenever they met an obstacle, the planners showed great flexibility in working around it and coming up with new ideas.
It is already known that by 1999 the main ingredients of the final plan had been decided, and training had begun. Mohammed has revealed that he wrote a training manual for the hijackers that included instructions on how to study flight schedules, select flying schools and gather information from the Yellow Pages.
Binalshibh, whose eight years working as a bank clerk had taught him how to move money through the international financial system, was appointed "co-ordinator of the operations of holy Tuesday" and became a personal favourite of bin Laden.
He has told interrogators he tried to get pilot training in Holland, but abandoned his attempts to join the other hijackers after his fourth application for an US visa was rejected.
The two men have confirmed that the September 11 targets had been chosen by June 2000. Over the next year, a series of meetings was held to update al-Qaeda leaders on progress. One took place in the mountains of Afghanistan in February 2001, another at Tarragona in Spain in July 2001.
The planners were thorough and carried out test runs on aircraft, smuggling box cutters on board to see if they would be picked up by security.
The whereabouts of Mohammed and Binalshibh have not been revealed by the US authorities. Asked whether torture was being used on the two men, J.Cofer Black, the US State Department co-ordinator for counterterrorism, has said: "All I can say to that is that there is a before and an after September 11." He added: "We have taken off our kid gloves."
However, according to the information leaked to Der Spiegel magazine, Binalshibh began to talk while he was still in the custody of Pakistan's intelligence service.
Mohammed was less co-operative, spending the first two days of his captivity crouching on the floor of his cell and reciting verses from the Koran.
Since then Mohammed has revealed details of much of the network he built up in the US to destroy bridges, planes, trains and fuel supplies.
He has admitted that one of his associates was Iyman Faris, a Kashmiri truck driver who was jailed for 20 years last week in Virginia after he admitted scouting New York's Brooklyn Bridge for a possible attack.
There is some suspicion that a few al-Qaeda operatives have been turned by their US captors in an effort to break down al-Qaeda's international structure further.
Mohammed has admitted that after September 11, while he was still on the run, he continued to plan attacks in the US, including one scheme to blow up petrol stations in New York and Washington.
The eventual fate of Mohammed, Binalshibh and the other senior members of al-Qaeda is unclear. Because of their importance they are not being held at Guantanamo Bay in Cuba, where less senior members of the organisation are incarcerated.
In the end they probably face life imprisonment and even execution. Binalshibh, at least, appears to have no regrets. If he is released or escapes, he has told his interrogators, his first act will be to "kill 1000 Americans".