Residents of this city's embattled Sadr City district are growing increasingly anxious that an escalation in fighting is imminent. They reported that soldiers with loudspeakers warned people in one section to move out, while others said that on Thursday, for the first time, the US carried out daytime airstrikes.
The vast sector of 2.5 million mostly poor Shiites has been the scene of sporadic and sometimes intense fighting for seven weeks as Iraqi and US forces have pushed in to rid the area of militiamen loyal to the Shiite cleric Moqtada al-Sadr. But Thursday's fighting, which officials in Sadr City hospitals said left at least 11 Iraqis dead, surprised some residents with its timing.
"We've had this kind of attack at night, but this was the biggest attack we've had in the daytime," said Abu Hawaraa, a media adviser to the Sadr movement's office in Sadr City. He said US forces also entered a normally quiet northern section of the district.
That incursion followed two militant rocket attacks in three days on central Baghdad parks. Thursday's rocket fire killed two people in a park along central Sadoon Street.
The US has increasingly relied on airpower – unmanned drones, helicopter gunships, and bombers – to carry out the antimilitia campaign in Sadr City, saying such methods more accurately reach targets in such crowded urban settings. US and Iraqi military officials accuse the militants of using residents as human shields as they carry out mortar and rocket attacks on the fortified Green Zone of Iraqi and US government offices a few miles south.
The two central Baghdad parks most likely were hit by rockets aimed at the Green Zone but that fell short, Iraqi officials said. US military officials have said the mortar and rocket fire is hitting a wider swath of central Baghdad as launch teams search out new and more distant launch sites.
The US military confirmed Thursday that helicopters fired rockets into buildings where individuals were assembling a rocket-launching system. Aerial surveillance confirmed that at least two militants at the site were killed, said Lt. Col. Steven Stover, spokesman for Multi-National Division Baghdad. He also denied reports that the US rockets hit a mosque, saying overhead video showed the nearest mosque to be more than 300 feet from the buildings hit.
It was the barrage of what the US military calls "indirect fire" on the Green Zone that drew it into the fighting in Sadr City – a fight that Iraqi Prime Minister Nouri al-Maliki started in late March as part of his stated goal of disarming Iraq's Shiite militias. In reality, that has meant a fight with Mr. Sadr's Mahdi Army militia and other militants more or less loyal to him.
Iraqi health officials reported Wednesday that the toll in the Sadr City fighting had surpassed 1,000, while on Thursday humanitarian agencies said delivering food, medicine, and other assistance to the neighborhood – sometimes reduced to one entry and exit – was becoming more difficult.
Meanwhile, Sadr City residents in the embattled southeast corner of the district reported that soldiers – some said Iraqis, others said Arabic speakers in US military vehicles – used loudspeakers to encourage residents of the area to leave. The US military called the reports "rumors," but some residents said the messages confirmed speculation running through the neighborhood for days that the government is planning a major offensive.
Earlier this week, Mr. Maliki said he would not call off the battle with what government officials say are illegally armed outlaws operating in Sadr City.
The US military has tried to avoid being drawn into a fight with Sadr, recently limiting its references to the Mahdi Army and instead blaming the Sadr City fighting on "criminals" and "special groups" that it says are armed and trained by Iran.
But almost daily American involvement in the fighting, usually to back up Iraqi forces who have sometimes been overpowered by the militants, has brought US forces into skirmishes with Sadr supporters. Last week, Sadr confirmed in a statement that his fighters are authorized to fight what he considers the "occupying forces."
The US incursion into northern Sadr City that residents described suggested the US may be broadening its involvement in the fight to areas outside the southernmost sector it has said it wants to rid of indirect fire launching. Part of the US plan is to build a wall around the southern third of Sadr City to secure it from the rest of the district.
The US focus on the southern part of Sadr City left residents all the more surprised by the fighting they described in the northern section outside the security wall.
"We did not expect that," Abu Hawaraa said, adding that it led to a fight that left several houses destroyed. "The Americans came in with Humvees and tanks, but some of those vehicles did not get out," he said. "I saw by my own eyes that two of the humvees" and at least two other vehicles were destroyed.
• Awadh al-Taiee in Baghdad contributed reporting.