necessary myth
In politics, a necessary myth is what the powerful elite creates to fill an ideological or spirtual vacuum in society, with the purpose of giving the populace something to believe in. The myth can be a certain religious idea, the promise of a better future for all, or if everything else fails, the promise of protecting us from the nightmare of terror and nuclear holocaust.
Alqaeda as an extraodinary well organized and powerful network with tentacular reach was a myth created by the Neo-Conservatives. It was a necessary myth cogitated out of whole cloth by these to get a firmer grip on power and farther their misguided agenda.