Ever since the upsurge of sectarian tit-for-tat killings began in February, with the destruction of the Golden Mosque in Samarra, many districts in Baghdad have turned to their "local guards," as they call them, for protection.
One can tell where the most frightened live, by the zigzag of obstacles -- palm trunks, old air conditioner units and unused cars -- placed at night to slow approaching vehicles.
Local gunmen take position on the streets and sometimes on the roofs of surrounding buildings.
In an attempt to differentiate the defenders from the aggressors, the U.S. Army in the most troubled spots has started to issue weapons licenses to people guarding their homes.
Few question the need for defensive measures. In a single day this week, at least 34 bodies have turned up across the city; in the previous three days, another 62.
Yet the confusion about who is behind the attacks means that everyone, even the police, is viewed with suspicion after dark.
Last month, a gunbattle raged for two days in the Adhamiya district, a Sunni area. Its neighborhood watch fought a pitched battle when police units entered after an insurgent attack was launched on a nearby Iraqi army checkpoint.
Word spread that they were members of the Badr Brigade, a Shi'ite militia that Sunnis blame for hundreds of kidnappings and killings.
Omar bin Abdulaziz Street, the thoroughfare that passes through the center of Adhamiya, was racked by gunfire from assault rifles, machine guns and the occasional rocket-propelled grenade as the police were caught in crossfire from surrounding buildings.
Loudspeakers in mosques blared slogans praising the "heroes of Adhamiya" and called on them to "defeat these aggressors."
Fighting stopped only when the U.S. Army moved in. For an area long considered a hotbed of rebellion, it is ironic that the presence of the Americans is now seen as a sign of protection from the terrors of sectarianism.
So widespread is the distrust of Iraq's security forces that the Defense Ministry has issued a statement telling people not to allow army or police to enter their homes at night unless they "are accompanied by coalition forces."