According to a Defence Intelligence Agency (DIA) Intelligence Information Report (IIR), obtained by the Judicial Watch, information about the plot came from an unidentified human intelligence source that provided authorities with copies of eight Arabic letters containing details of the al Qaeda plot.
For 13 years the subject report was classified "SECRET", until it was finally declassified and released to Judicial Watch on August 29, 2013, a media release said.
The hijack team was to consist of an Arab, a Pakistani, and a Chechen, it said.
"Chechen withdrawal from the plot delayed the operation. Sheik Dzabir, a 40-year-old Saudi with ties to the House of Saud, directed the operation. Advanced warning of the plot was disregarded because nobody believed that Osama bin Laden or the Taliban could carry out such an operation," the report said.
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According to the report, al Qaeda, the Taliban, and Chechen Islamic militants all had substantial operating support bases in Hamburg and Frankfurt.
It also revealed the existence of a secure, reliable terrorist-sponsored route to Chechnya from Pakistan and Afghanistan through Iran, Turkey, and Azerbaijan.
In January 2000 there was a two-day hijack planning meeting between bin Laden and Taliban officials in Kabul.
"The details of names, addresses, and such, from this reporting should have provided 'actionable intelligence' for any number of US anti-terrorist operations," said Judicial Watch President Tom Fitton.
It was only months later that al-Qaida operatives, mostly from Saudi Arabia, hijacked four American passenger jets at the same time, crashing one into the Pentagon, two more in the Twin Towers in New York, and losing the fourth when passengers apparently fought back and it crashed into a Pennsylvania field, missing its apparent intended target, the White House.