Al Qaeda terrorists wanted to launch 'more spectacular' attacks on the United States using as many as ten jetliners, but the plan was scaled down following internal differences in the terror network, the panel probing the September 11 strikes has found.
"Senior al Qaeda officials initially wanted to mount even more spectacular attacks ... using ten jetliners on the east and west coasts of the US causing massive casualties," the report of the National Commission on Terrorist Attacks on the United States said.
In addition to the targets that were hit on September 11, 2001, mastermind behind the attacks Mohammad Atta had proposed to crash the hijacked planes into CIA and FBI headquarters, unidentified nuclear power plants and the tallest buildings in California and Washington states, it said.
"The centrepiece of his original proposal was the tenth plane, which he would have piloted himself, it said.
Instead of crashing it in a suicide attack, Atta would have killed every adult male passenger on the plane, contacted the media from the air and landed the aircraft at a US airport, the report said.
It added that he would then have made a speech denouncing US policies in the Middle East before releasing all thee women and children.
When bin Laden finally approved the operation, he personally scrapped the idea of using one of the hijacked planes to make a public statement, the report said.
The Commission staff found that 'internal disagreement among the 9/11 plotters may have posed the greatest potential vulnerability for the plot'.
The Commission report said bin Laden strongly favoured targeting the White House and urged Atta and other senior leaders to agree. But Atta was concerned that the presidential mansion was too difficult to hit, and backed the US Capitol instead.
The targets were finalised as late as two days before the attack, the report said
The clearest example is a serious rift that developed between Atta, whom bin Laden had designated as the "emir" of the plot, and Ziad Jarrah, one of the other trained pilots, it said.
Jarrah was more gregarious and seemingly westernized than his compatriots, and he pined for his girlfriend, it said.
He had married her in an Islamic ceremony not recognized by German law, and he called her on an almost daily basis.
The breaking point appears to have come in July 2001, when Jarrah was taken to the Miami airport by Atta and issued a one-way ticket to Germany.
Although Jarrah would rejoin the plot in the next month, the panel concludes that Atta 'may have been preparing another al Qaeda operative, Zacarias Moussaoui, to take Jarrah's place' and that he was intended 'as a potential substitute pilot'.
Moussaoui was arrested in Minnesota in August 2001, and charged as a conspirator in the September 11 plot.