WASHINGTON - For all their coordinated carnage, the September 11, 2001 attacks sprang from a shifting and problem-plagued plot that some terrorist leaders wanted to call off, an official report said Wednesday.
A preliminary report issued by the national commission investigating the assaults on New York and Washington that left 3,000 people dead said it would be a mistake to consider them the result of a fixed plan executed to near perfection.
"The 9-11 conspirators confronted operational difficulties, internal disagreements and even dissenting opinions within the leadership of al-Qaeda," said the staff report released at the panel's last set of hearings here.
Conceived in 1996, approved by al-Qaeda chief Osama bin Laden in 1999 and set in motion later that year, the plan triggered a rift among the leadership of the Afghanistan-based group in the months before the attacks.
Several senior al-Qaeda figures thought they should defer to Taliban leader Mullah Omar, who opposed attacking the United States, the report said, quoting statements by captured al-Qaeda members. Others feared a massive US military response.
"Although he faced opposition from many of his most senior advisers ... bin Laden effectively overruled their objections and the attacks went forward," the commission investigators said.
The report said the operation went through several changes in tactics and timing before 19 al-Qaeda hijackers commandeered four airliners, ramming two into the twin towers of the World Trade Center and a third into the Pentagon.
The originator of the plot, Khalid Sheikh Mohammed, had initially envisioned hijacking 10 planes, with a target list including CIA and FBI headquarters, and blowing up several aircraft over the Pacific at the same time.
Bin Laden scaled the plan down and scrapped the Asian end as too difficult to coordinate with the US attacks. But he urged on several occasions that the timetable be moved up.
At one point, he pressed to launch the strikes in the summer of 2000, shortly after Israel's soon-to-be prime minister, Ariel Sharon, made a highly controversial visit to a disputed holy site in Jerusalem.
Bin Laden later pressured the hijackers to strike in May 2001 and in June or July when Sharon would be visiting the White House. Each time he was told the commandos were not ready, the report said.
A few weeks before September 11, friction developed between two of the "pilots" from Al-Qaeda's so-called Hamburg cell: Mohammed Atta, the presumed ringleader of the hjackings, and Ziad Jarrah.
Jarrah even reportedly threatened to pull out, obliging Khalid Sheikh Mohammed, who has since been captured by the Americans in Pakistan, to bring in Moroccan-born Frenchman Zacarias Moussaoui as a replacement.
Moussaoui is the only person charged in the United States in connection with the attacks that left the world's superpower reeling and triggered its invasions of Afghanistan and Iraq.
The commission report said the hijackers also came close to tripping themselves up in the final stages of the operation.
Jarrah was ticketed for speeding as he drove through the eastern state of Maryland two days before he ended up on United Airlines Flight 93, which crashed in the Pennsylvania countryside after an apparent passenger revolt.
Atta and one of his accomplices, Abdul Aziz al Omari, flew from the northeastern US city of Portland, Maine to Boston and almost missed American Airlines Flight 11 that crashed into the World Trade Center. Their luggage didn't make it aboard.
The report said the operation cost 400,000-500,000 dollars to execute, with 270,000 dollars of that spent in the United States. The origin of the money is still not known and it did include the cost of the Afghan camps where they were trained.
The document released Wednesday will be incorporated into a final report to be issued next month by the commission of five Republicans and five Democrats which will hold a final day of hearings Thursday.