Russ Baker offers some speculation on who was behind the September 11, 2012 attack in Benghazi. I happen to have some speculations of my own about the incident, which I posted in a comment there and decided to reprint here:
1. Karl Rove showed genuine surprise that Obama won the election, instead of Romney. (I suspect that the Republican plot to win Ohio didn't work this time). From this I think we can assume that CIA director Petraeus had expected he would have a new boss after the election.
2. The USS Cole incident happened shortly before the election in 2000, and served as the final preparatory attack that made the official story of 9/11 credible: Al Qaeda had been attacking us abroad for years, so it was to be expected that they would eventually attack us at home.
3. Expecting that a Republican administration would be in place in 2013 (which would provide the needed protection from a real investigation), a new, larger false flag terrorist attack in the U.S. had been planned, to justify a total police state.
4. Thus, the Benghazi attack was also a preparatory attack, modeling the USS Cole incident, that would have served as a way of making the official story of the coming 2013 attack look credible.
5. But Obama unexpectedly won the election, and Petraeus's resignation was immediately demanded.
6. However, we can expect something similar in 2016.