Overall, the CIA’s depiction of the events that led to the death of Ambassador Christopher Stevens offers new insight into US operations in the eastern Libyan city. It suggests that the small and lightly secured diplomatic mission served as a kind of cover for a larger but covert US intelligence presence, centered in an “annex” located about a mile from the consulate. This intelligence-gathering was focused on an area where Islamist extremists and Al Qaeda-affiliated militants were known to operate.Well, this brings the attack on the compound that killed 4 new Americans, including the Libyan ambassador, into a whole new light, and explains some of the reasons for the shifting storyline.
I can think of several possible explanations for the attack now:
1) classic revenge-type anger blowback by the militants on to the CIA, if the CIA was trying to control the militants
2) an attack by the militants on the CIA faction as part of a cover-up by the CIA. Possibly the Ambassador was being tipped off on al-CIA-duh activities by the CIA contractors who were killed.
3) a deliberately instigated attack by militants at the behest of the CIA, to create some sort of October-surprise incident to influence the presidential election
4) some combination of 1 and 3 or 2 and 3
UPDATE-- this piece from an ex-CIA guy says it was blowback, FWIW. But some interesting info in there and worth a read.