During Thursday’s Hill briefing on the assault on the US consulate in Benghazi, Sen. Lindsay Graham says he asked the briefers how many US security personnel were assigned to protect the compound.

Their answer: “We’ll get back you on that.”

While Secretary of State Hillary Clinton and her team come up with that number, some details on the security at the compound are emerging. They paint a picture of extreme negligence.

The Libyan owners of the main villa rented by the diplomats was surprised at how little, beyond some barbed wire and security cameras, they added to the walled residential compound, on a quiet street where volatile militiamen were free to roam.

Most striking was the absence of a second line of defense inside the main gate on to the street; that left the few guards in the compound little chance of holding off a crowd once the gate, which showed no sign it had been forced, was swung open.

That consulate had already been attacked in June, with an IED. The British consulate and the Red Cross mission, which were on the same street as the US consulate, had also been attacked. But no serious security modifications were reportedly made to the compound.

The main gate was manned by Libyans who had no secure position from which to confront an assault. Inside, there were neither towers nor firing positions for U.S. security personnel. There were no U.S. troops, and, according to congressional staff sources, just five American civilian security staff.

Well, at least we have an answer to Graham’s question: Zero.