We hired who for security?
In addition to the five U.S. diplomatic security agents stationed on the compound and the CIA's "rapid reaction" team, located at an annex a little more than a mile away, the United States relied on a local militia called the 17th of February Brigade to guard the consulate against intruders. According to the Washington Post, the decision was probably made for lack of a better alternative (international law requires the Libyan government to furnish protection for foreign diplomatic outposts that it's simply incapable of providing), but it ultimately proved costly.
When assailants breached the diplomatic compound on Sept. 11, the two members of the 17th of February Brigade on duty apparently hid on the roof while their off-duty comrades failed to respond to the CIA's repeated requests for backup. Given this miserable failure, we should expect questions about the wisdom of trusting a rag-tag collection of militiamen with ties to the Muslim Brotherhood -- all the more so because McClatchy has reported that, while most embassies hire local security, "only the United States of the 10 or so foreign missions here allowed the local militia to be the first line of defense."
Both the CIA and the Pentagon have released timelines of the Benghazi attack, but they are sparse and contain few points of convergence to suggest how or whether they coordinated their responses. (Both timelines also conflict with the accounts of local witnesses, who say the attack began as many as 15 minutes earlier than the United States says it did.)
The Pentagon's timeline begins simply with: "9:42 p.m. -- Armed men begin their assault on the U.S. Consulate." It provides no explanation of how Defense Department officials learned of the attack or whether they were in contact with the CIA's rapid response team on the ground. The appearance of an unarmed surveillance drone in both timelines suggests some level of cooperation, especially since the CIA's timeline states that the drone failed to observe the mortars that eventually killed CIA contractors Glen Doherty and Tyrone Woods, but lawmakers will likely want to fill these and other holes in the current accounting.