At 9:40 p.m. on Sept. 11, when CIA officials at the agency's Benghazi facility learned of the attack on the U.S. consulate one mile away, they took two separate actions. First, a seven-person security force prepared to leave to help defend the consulate. Separately, according to Greg Miller's report on the night's events, agency officials "sought, without success, to enlist Libyan militias that had been hired to provide security for the diplomatic outpost in Benghazi."

The degree to which the CIA succeeded or failed in upholding what The Wall Street Journal says was a secret agreement to provide "emergency security" for the consulate appears to be the subject of some dispute. But one thing that perhaps the State Department and CIA might agree on, based on the information publicly reported so far, is the degree to which the Benghazi consulate was failed by its Libyan security forces.

Though U.S. officials seem to have largely refrained from pointing fingers at their Libyan counterparts, one consistent feature of the drip-drip of information about the Benghazi attack seems to be that U.S. agencies felt they were not getting the security they expected and perhaps needed from the host country.

Still, it's not shocking that the nascent Libyan state would be unable to meet those expectations, and its failure raises questions about why the U.S. agencies were caught off guard by this on Sept. 11.

The genesis of the February 17 Brigade, which was officially providing the consulate day-to-day "primary" security, goes back to last year's Libyan civil war. When the war ended, this group of volunteer militiamen, like many others, held onto their guns and provided basic state functions for a country still recovering from not just civil war but decades of Moammar Gaddafi's careful dismantling of any civil society or agency powerful enough to even hint at challenging him. Those militia functions have centered on security, including for the U.S. consulate in Benghazi, where traditional police or military forces are still not strong enough to fill the role on their own.

A few days after the Sept. 11 attack, a New York Times report called the February 17 Brigade "eastern Libya’s most potent armed force," noting that it "nominally" reports to the Libyan defense ministry. The command link between Tripoli's senior leaders and on-the-ground militias has proven weak, but the central government still relies heavily on them.

International law requires that a host country – in this case, Libya – guarantee security for foreign diplomatic buildings. Libya's guarantee was the February 17 Brigade, perhaps the best it could do. The U.S. consulate, in turn, accepted the militia as its guards and even worked with the brigade to set up a "quick reaction force" in the case of attack, according to documents that the Post's Michael Birnbaum recovered at the site. The brigade had shown past conviction in its mission, at one point that spring helping to rescue a U.S. foreign service officer from a firefight.

Still, security in Benghazi seems to have been consistently problematic. Anti-American militants had made a number of attempts on the consulate and had launched more successful attacks against a number of Western diplomatic and NGO buildings in the city. Ambassador Christopher J. Stevens and his staff had appealed to Benghazi's police chief and the Libyan foreign minister for more security, according to unsigned letters recovered at the consulate by two Al-Aan reporters, articulating pointed concerns that the Libyan forces were insufficient.

A few days before the attack, two mercurial local militia leaders had threatened to cease protecting the consulate after Libya's national election because they suspected the United States was offering its support to a rival politician. There's no reason to believe that the militias (which are separate from February 17) withdrew before the election, but the incident underscores concerns over the militias' seriousness about its mission.

Stevens turned out to be right about the Libyan security. When the Sept. 11 attack on the consulate began, neither the Libyan guards nor the "quick reaction force" proved sufficient, if the latter ever materialized at all. The CIA account has the agency immediately trying to raise local Libyan militias to help respond, unable to even get an answer.

Further efforts to raise the militia seem to have achieved little. When a larger U.S. reaction force arrived from Tripoli at the Benghazi airport, they were forced to haggle with locals for transportation into town – something that February 17 Brigade might have provided. A "heavily armed Libyan military unit" did arrive at the CIA's facility around dawn the next morning, though as Miller points out in his story, it's not at all clear where they had been for the preceding 12 hours.

At the time, this must have been alarming and deeply frustrating for CIA and State Department officials struggling to contain the Benghazi firefight using limited American resources. In retrospect, though, it largely serves to underscore the already well-known problems with Libya's militia-based system. The entire reason that the U.S. consulate was using February 17 Brigade, after all, was because the state was not able to provide security on its own.

That inability is rooted in some tough realities about Libya's post-war government, which is still politically fractured and institutionally weak. These problems are not the responsibility of the U.S. State Department or the CIA to solve, but they also were presumably no secret to the U.S. agencies relying on Tripoli for security.

In most countries, in the event of an attack on American diplomats, U.S. officials would contact the host country's military or security services. But when the only numbers you can call are the cell phones of citizen militiamen, the consulate's security is resting in large part on the ability and desire of those militiamen to answer their phones late on a Tuesday.

Based on the concerns that Stevens and his staff had expressed to the Libyan government, it does not seem that he had been happy with the militia's security even before the attack. It's difficult to understand why the State Department or CIA would have thought that February 17 Brigade would have been able to repel a surprise attack on the consulate or that the Libyan government would be able to fill the gap in a crisis. Given that the State Department saw the risk of such an attack as high, why continue relying on the militiamen for day-to-day consulate security?