From Dr. Michael Ledeen (emphasis added is mine):
Killing Americans serves several purposes in the war being waged against us (we have yet to seriously engage against our known enemies): first, it’s what the war is all about. They want us dead or dominated. Second, it helps recruitment, which had dropped after the defeat of Iran, Syria, and al-Qaeda in Iraq. Morale had also dropped, and stories claiming that the top American in Libya had been raped before he was executed feeds the blood lust of jihadists, whose language and fantasies are rich with such images. Third, it enhances the power of the unseen moving hand. Fourth, it discourages our current and would-be friends and allies.
No serious person believes that an obscure movie shown to less than a dozen people many months ago was the “cause” of the simultaneous assaults in Cairo and Benghazi. Or that the assaults were unrelated, let alone spontaneous. Or that there was no state actor involved in the operation.