According to the book- The Hunt for KSM: Inside the Pursuit and Takedown of the Real 9/11 Mastermind, Khalid Sheikh Mohammed, terror head Osama bin Laden refused to back the plan when it was first proposed in 1996. The plan was actually brought to the forefront by Mohammed and Abdul Hakim Murad, the mastermind behind Manila Air plot.
The book also throws light on the difficulties faced by the CIA and FBI during their chase to track down the al-Qaeda after 9/11.
The book read, "(Murad said) If you did this you needn’t go through the precise and exacting process of building bombs. You didn’t need bombs at all."
"Murad’s idea essentially converted the airplanes into missiles. Bin Laden dismissed this as inconsequential. We could do it on a broader scale, Mohammed said. Flying airplanes is not that difficult. Even Murad has a license".
"We could train pilots in the United States, then when they were ready simultaneously hijack as many as ten planes from the East and West coasts of the United States and fire them all into buildings on the ground".
"Then Mohammed said, I would land a final airplane in the middle of the United States and walk out onto the tarmac and explain to the Americans why this terrible thing had happened and what they ought to do to prevent it from happening in the future".
"Bin Laden was noncommittal. He told KSM (Mohammed) that he appreciated the ideas and would give them due consideration".
It took three years for Bin Laden to change his mind and he only supported a ‘slimmed down’ plan that will use only four or five planes.
The book also said that before the horror that struck US, the CIA was 'confident that Al Qaeda posed no threat to the US' and 'failed to recognise the danger KSM (Mohammed) posed'.