Adam Housley, writing for Fox News, had this on the Benghazi fiasco:
On the night of the Benghazi terror attack, special operations put out multiple calls for all available military and other assets to be moved into position to help—but the State Department and White House never gave the military permission to cross into Libya[.]
Normal ops in locations like Benghazi has the Chief of Mission in charge—Ambassador Chris Stevens in this case—who has procedures for calling for help and transferring authority in exigent circumstances. With Stevens (and such protection as he was allowed to have) trapped, his “distress button” was pushed, and authority was transferred to State, where again in the Benghazi case, response oversight and authority transferred to then-Secretary Hillary Clinton and one of her Undersecretaries, Patrick Kennedy.