In mid-August, the Mossad team running the Hamburg cell in …

In mid-August, the Mossad team running the Hamburg cell in Boston reported to Tel Aviv that the final plans for 9/11 were set. The Florida-based Mossad cell reported that the documented "presence" of the Arab cell members at Florida flight schools had been established.
The two Mossad cells studiously avoided any mention of the World Trade Center or targets in Washington, DC in their coded messages to Tel Aviv. Halevy covered his tracks by reporting to the CIA of a "general threat" by an attack by Arab terrorists on a nuclear plant somewhere on the East Coast of the United States. CIA director George Tenet dismissed the Halevy warning as "too non-specific." The FBI, under soon-to-be-departed director Louis Freeh, received the "non-specific" warning about an attack on a nuclear power plant and sent out the information in its routine bulletins to field agents but no high alert was ordered.
The lack of a paper trail pointing to "Al Oaeda" as the masterminds on 9/11
which could then be linked to Al Qaeda's Mossad handlers, threw off the FBI.
On April 19, 2002, FBI director Robert Mueller, in a speech to San Francisco's Commonwealth Club, stated: "In our investigation, we have not uncovered a single piece of paper either here in the United States, or in the treasure trove of information that has turned up in Afghanistan and elsewhere that mentioned any aspect of the September 11 plot."