Before most Americans had heard the name Osama bin Laden, Israel's Mossad was on to him. In 1995, when unknown assailants tried to kill then-Egyptian President Hosni Mubarak in Ethiopia, the CIA and the Egyptian intelligence service requested the Mossad's assistance in investigating the incident. The Mossad discovered that Iran and a hitherto unknown mujahedeen group were jointly responsible for carrying out the attempted assassination. Notable among these mujahedeen—veterans of the war against the Soviets in Afghanistan who had found refuge in Sudan—was a certain wealthy Saudi by the name of bin Laden.

The...