The religiously mixed middle-class neighborhoods of Al-Amal and Hurriyah that straddle Baghdad's famously dangerous airport road are turning into the front lines of the deepening civil war in Iraq.
It's in these two neighborhoods where men are murdered for having Shiite- or Sunni-sounding names; where Moqtada al-Sadr's Mahdi Army is hailed by some as protectors; and where former supporters of the Sunni insurgency aimed at driving out US forces now look to the US for protection. They are case studies in how old tribal animosities are flaring anew at a time when Iraqi security forces and US troops seem stretched too thin to react.
"The mortars came down around the house for hours, and then the machine guns opened up just up the street,'' says Mohammed al-Jiburi, member of a large Sunni tribe that is well represented in Al-Amal, following running battles between Shiites and Sunnis Sunday. "Did the police come? Did the Americans come? No. I've sent my wife and the kids away to a relatives on a farm," he says. "I'm staying put because I can't afford to have the house looted."
For the moment, Shiite fighters loyal to Mr. Sadr have driven dozens of Sunni families from both neighborhoods in recent days, say local residents and police.
The strengthening role of Sadr's Mahdi Army presents a disturbing window onto the possible path of this war. While they claim to be only targeting the "deserving" and are acting to protect their coreligionists, more and more the militia is taking a lead role in the sectarian battle unfolding daily on the ground in Baghdad.
"Some of us told them that our Sunni neighbors aren't terrorists, they should be left alone," says a Shiite man, who asked that his name not be used, estimating that five Sunni families have left his street in the past week. "They wouldn't listen – and some Shiites are now saying the solution is to drive the Sunnis out."
Evidence on the ground shows that militia groups have grown stronger since the current government took power early this year. While US advisory groups, such as the Iraq Study Group, are calling for mediation and reconciliation, street-level combatants seem determined to kill as many representatives of the other side as possible.
Sunni insurgents have responded with a stepped-up bombing campaign that has killed indiscriminately – but more Shiites than Sunnis – such as in the attack that murdered at least 60 mostly Shiite day laborers Tuesday. Most of the victims were poor Shiites from Sadr City.
In a world with violence so indiscriminate, coexistence in Baghdad's traditionally mixed neighborhoods is becoming impossible for hundreds of families.
On Sunday in Al-Amal, a Shiite man was shopping with his son when he saw black clad Mahdi Army militiamen toting rocket-propelled grenades near the main shopping street. "Get that kid out of here," they shouted. "We're about to hit the Americans."
He rushed off, and a few minutes later heard a deafening explosion. "We could see a burning Humvee from the roof of my house,'' he says, asking that his name not be used. "Everyone seems like they're everyone else's enemies. My Sunni neighbors used to vow they'd never be driven out, but now they're going."
The latest exodus of Sunni families from their neighborhoods began on Dec. 8 after a suicide car bomb on a nearby gas station. Mahdi Army operatives slid leaflets under Sunni residents' doors, accusing them of aiding insurgents and telling them to get out. Some did, but others shrugged of the threats.
The next day, the attack came. In Al-Amal, the mortars started landing shortly before 7 a.m. One scored a direct hit on a Sunni mosque, outside of which Iraqi Interior Ministry commandos set up a checkpoint Tuesday to prevent further attacks.
"My father, he's an old man, he took shrapnel in the leg. We don't want this to continue, but no one seems able to stop it,'' says Mr. Jiburi.
In Hurriyah, Saturday's fighting began a little later. There, Shiite militiamen fanned out through the neighborhood and shot at least four people, according to local police. Over the past week in the two neighborhoods, about 20 people have been killed – about 10 in the fighting over the weekend and the others by death squads and car bombs.
While that is a low number of overall deaths in Iraq, it has a chilling effect when seen against the backdrop of violence in and around Baghdad.
"Originally, months ago, the problem in the neighborhood was between two tribes – the Jiburi and the Maksosy," says Wissam Hamed, who lives in Hurriyah. "But the problem is the Jiburi are Sunnis and the Maksosy, Shiites. It became about religion pretty quickly."
Mr. Hamed says that over the past day, Interior Ministry commandos have filtered into the neighborhood. While he says he remains leery of them – many Iraqis allege the units are heavily infiltrated by the Mahdi Army and other militias – he says they've been doing a decent job since they arrived. "For now they are keeping the people separated and the fighters out. Usually they leave after a few days. I hope they stay."
• An Iraqi reporter, not named for safety reasons, contributed to this report from Baghdad