Although the Mossad's warnings regarding 9/11 appear to exonerate it, that is not the case. Former Mossad case officer Victor Ostrovsky in his two excellent books By Way of Deception and The Other Side of Deception demonstrates that the Mossad often uses useless warnings as a way of making themselves look innocent when in fact the opposite is true:

http://www.marwenmedia.com/articles_images/BookReview.html

"Admony, then the head of Mossad, decided they would simply give the Americans the usual general warning, a vague notice that they had reason to believe someone might be planning an operation against them. But this was so general and so commonplace, it was like sending a weather report; unlikely to raise any particular alarm or prompt increased security precautions. In the six months following receipt of this information, for example, there were more than 100 general warnings of car-bomb attacks. One more would not heighten US concerns or surveillance."

"Admony, in refusing to give the Americans specific information on the truck, said, "No, we're not going to protect the Americans. They're a big country. Send only the regular information."

Once one understands the methodology of the Mossad and its management of false flag attacks - as well as the massive involvement of the US - Israeli axis in manufacturing the "War on Terror" - to accept the idea that the Mossad is innocent because it gave weak and useless warnings to its partner in crime the CIA becomes absurd.