In the beginning of the original TV series, "Mission Impossible", starring Peter Graves.....his character, Mr. Phelps, listened to a tape recorder outlining their next mission.
It always included a caveat...."if your fail or get captured, the US Government will disavow any knowledge or association with you".
IMO, that's what essentially happened in Benghazi that fateful night.
....or it could have been planned all along to have everybody at the "Consulate" slaughtered...as Dead Men tell no tales.