They were watching this in real time. They knew on the spot this was no damn demonstration. They watched the whole thing for SIX HOURS and did nothing.
The agent’s call for help at the very beginning, to Washington, the Libyan authorities, and the Embassy in Tripoli, gets no result of any help;
Background Conference Call With Senior State Department Officials
October 9, 2012
http://www.state.gov/r/pa/prs/ps/2012/10/198791.htm
“...I neglected to mention from the top that that agent from the top of this incident, or the very beginning of this incident, has been on the phone. He had called the quick reaction security team, he had called the Libyan authorities, he had called the Embassy in Tripoli, and he had called Washington. He had them all going to ask for help.”