The Sept. 11 attack on the U.S. consulate in Benghazi killed four Americans, including U.S. Ambassador Chris Stevens, raised questions about the stability of post-Gaddafi Libya, and ultimately became a major political controversy in the weeks ahead of Tuesday's U.S. presidential election. The political debate around Benghazi has often turned on an implicit (and sometimes quite explicit) question: Who messed up? That question hasn't been easy to follow, both because of the slow trickle of information about the incident and because so much of the domestic conversation has been colored by its political implications.

This is an attempt to objectively consider the various individuals and groups connected to the Benghazi incident, what's been publicly reported about their roles so far, and what that information suggests about their potential responsibility.

Because the picture of what actually happened before, during and after the attack is so incomplete and hazy, these appraisals are necessarily speculative and should be taken with a grain of salt. Rather than a definitive determination of fault, they should be considered estimations based on the publicly available information – a picture that could change dramatically as new information comes out. Still, taken together, they show both how widely dispersed the blame could be and how relatively minor, individual mistakes may have added up to something larger.

State Department: A mid-level denial to boost security

A mid-level official at the State Department had denied requests for a handful of additional security officers at the Benghazi consulate, despite a marked uptick in violence and the shortcomings of Libyan security forces. Warning signs, including a June bombing outside the consulate, did not appear to lead the department to beef up security. The largest request was for 12 additional men; there were five at the time of the attack. The State Department necessarily relies on its host government for security, and maybe in this case the CIA as well, although ultimate responsibility for State Department security would seem to rest with the agency itself. There's no evidence that the security requests went higher than the mid-level official.

Central Intelligence Agency: 'Emergency security' couldn't save ambassador

The consulate in Benghazi had a secret arrangement with nearby CIA forces that were to provide "emergency security." The Wall Street Journal said in reporting the arrangement: "The CIA’s secret role helps explain why security appeared inadequate at the U.S. diplomatic facility." A seven-person CIA security force responded within 50 minutes of the initial attack but, in the chaos of the battle, did not retrieve the ambassador. A number of observers have raised the obvious question of why the CIA did not see this attack coming, given its apparent scale. It's worth noting that Libya is awash in small arms and militias, which would seem to make monitoring them unusually difficult.

Pentagon: Quick-reaction force wasn't ready

A New York Times report on the Pentagon's Africa command found that "forces in the region had not been adequately reconfigured" to respond to the attack. The Africa command AFRICOM, formed in 2007 and responsible for all U.S. military in Africa, is still developing its quick-reaction force and had to "borrow" one based in Europe. "Critics say there has been a gap in the command’s quick-reaction capability, which the force would have helped fill," according to the Times. Still, the force would have been based in Sicily, so it's doubtful the troops would have been able to arrive in time to defend against the initial assault.

Ambassador Chris Stevens: Stayed in town despite seeing risk

As Foreign Policy's Blake Hounshell put it, "Nobody wants to say it, but Amb. Chris Stevens was a big boy and he made his own decision to go to Benghazi despite the risks. If he thought it was too dangerous, he should not have gone." And he had a reputation for jogging Libya's streets despite security threats. Still, Stevens clearly sought greater security in Benghazi from local and national Libyan officials. It's not clear whether or not he made similar appeals to U.S. officials, but he seemed to take the security situation seriously.

February 17 Brigade: Hired to defend consulate, unreachable during the attack

This Libyan militia, the most powerful security force in post-Gaddafi Benghazi, was officially designated to guard the consulate, fulfilling the Libyan state's responsibility. Stevens had made appeals to local and national Libyan officials complaining that their Libyan security was insufficient, reflecting concerns that February 17 wasn't up to the task. On the night of the attack, the CIA urgently tried and failed to raise the militiamen. That's a big deal, suggesting a degree of irresponsibility and/or incompetence. (There's no indication of malicious intent.) Still, given that this is a citizen militia fulfilling a role usually played by a country's military or domestic security services, how did its disappointing performance take U.S. agencies by quite such surprise?

Libyan government: Struggling to provide basic security

The Vienna Convention requires host countries to assume responsibility for foreign diplomatic buildings. Libya, it seems, was just not up to the task. Michael Birnbaum found officials and agencies "on autopilot as the new lawmakers plot alliances and betrayals over endless cups of coffee in Tripoli." Stevens had protested to senior officials that Benghazi's security was insufficient, although given that the consulate was relying on a citizen militia, it's not clear what Tripoli could have done. After four decades of dictatorship and the recent civil war, the central state just does not yet have a hold on basic security functions. Still, as with February 17, one question is whether or not the U.S. agencies should have been able to foresee these shortcomings.

Congressional Republicans: A 10 percent security budget cut

Some critics, including Vice President Biden, have noted that the GOP-led House of Representatives reduced appropriations for embassy security, which ultimately came to about 90 percent of what the administration requested, a drop of $270 million. Still, assuming that the cuts were proportional, it's hard to see this being decisive. Returning the funding to the full amount would have increased the number of dollars by only 10 percent; boosting the Benghazi security by 10 percent (from five guards to five and a half?) seems unlikely to have turned the tide.

President Obama, Secretary of State Hillary Clinton, CIA Director David Petraeus

The details of bureaucratic infighting over consulate security might seem enormously significant now that they have undergone such public scrutiny, but it's very difficult to imagine those disputes reaching top U.S. leaders beforehand. The U.S. has 200-plus embassies and consulates abroad; their security requests are not cabinet-level decisions. Barring some extraordinary revelation, the strongest case for top-level responsibility is that these people oversee the people who oversee the people who made the decisions about security in Benghazi. That's not nothing, but it's not exactly the next Iran-Contra affair, either.