On the outskirts of Falluja, tens of thousands of Iraqi soldiers, police officers and Shiite militiamen backed by Iran are preparing for an assault on the Sunni city, raising fears of a sectarian blood bath. Iran has placed advisers, including its top spymaster, Qassim Suleimani, on the ground to assist in the operation.
The battle over Falluja has evolved into yet another example of how United States and Iranian interests seemingly converge and clash at the same time in Iraq. Both want to defeat the Islamic State, also known as ISIS or ISIL. But the United States has long believed that Iran’s role, which relies on militias accused of sectarian abuses, can make matters worse by angering Sunnis and making them more sympathetic to the militants.
While the battle against the Islamic State straddles the borders of Iraq and Syria, the United States has approached it as two separate fights. In Syria, where the government of Bashar al-Assad is an enemy, America’s ally is the Kurds.
But in Iraq, where the United States backs the central government, and trains and advises the Iraqi Army, it has been limited by the role of Iran, the most powerful foreign power inside the country.
That United States dilemma is on full display in Falluja as the fighting intensifies.
Inside the city, tens of thousands of Sunni civilians are trapped, starving and lacking medicine, according to activists and interviews with residents. Some were shot dead by the Islamic State as they tried to flee, and others died under buildings that collapsed under heavy military and militia artillery bombardment in recent days, according to the United Nations.
In an extraordinary statement on Wednesday, Grand Ayatollah Ali al-Sistani, the world’s pre-eminent Shiite religious leader, who lives in Najaf in southern Iraq and is said to be concerned by Iran’s growing role in Iraq, urged security forces and militia to restrain themselves and abide by “the standard behaviors of jihad.”
The grim sectarian tableau in Falluja — starving Sunni civilians trapped in a city surrounded by a mostly Shiite force — provides the backdrop to a final assault that Iraqi officials have promised will come soon.
The United States has thousands of military personnel in Iraq and has trained Iraqi security forces for nearly two years, yet is largely on the sidelines in the battle to retake Falluja. It says its air and artillery strikes have killed dozens of Islamic State fighters, including the group’s Falluja commander. But it worries that an assault on the city could backfire — inflaming the same sectarian sentiments that have allowed the Islamic State to flourish there.
Already, as the army and militiamen battled this past week in outlying areas, taking some villages and the center of the city of Karma, to the northeast, the fight has taken on sectarian overtones.
Militiamen have plastered artillery shells with the name of Sheikh Nimr al-Nimr, a Shiite cleric close to Iran whose execution this year by Saudi Arabia, a Sunni power, deepened the region’s sectarian divide, before firing them at Falluja.
A Shiite militia leader, in a widely circulated video, is seen rallying his men with a message of revenge against the people of Falluja, whom many Iraqi Shiites believe to be Islamic State sympathizers rather than innocent civilians. Falluja is also believed to be a staging ground for suicide bombers targeting the capital, Baghdad, about 40 miles to the east. The decision to move on the city was made after several recent attacks in Baghdad killed nearly 200 people.
“Falluja is a terrorism stronghold,” said the militia leader, Aws al-Khafaji, the head of the Abu Fadhil al-Abbas militia. “It’s been the stronghold since 2004 until today.”
He continued: “There are no patriots, no real religious people in Falluja. It’s our chance to clear Iraq by eradicating the cancer of Falluja.”
Prime Minister Haider al-Abadi, who has stressed that civilians must be protected in the operation and ordered that humanitarian corridors be opened to allow civilians to leave the city safely, disavowed the militia leader’s comments.
Reflecting these concerns of sectarianism, and the deep sense of foreboding surrounding a battle for the city, a chorus of voices in Iraq and abroad has urged restraint.
In his statement, Ayatollah Sistani said: “The Prophet Muhammad used to tell his companions before sending them to fight, to go forward in the name of Allah, with Allah and upon the religion of the messenger of Allah. Do not kill the elderly, children or women, do not steal the spoils but collect them, and do not cut down trees unless you are forced to do so.”
The concern was amplified in a second statement, released during Friday prayers by a representative for the ayatollah, saying that “saving an innocent human being from dangers around him is much more important than targeting and eliminating the enemy.”
Accounts of dire conditions in Falluja have emerged from the few residents who managed to escape in recent days, Melissa Fleming, a spokeswoman for the United Nations refugee agency, told reporters in Geneva on Friday. She said that some residents had been killed for refusing to fight for the jihadists, and that those inside were surviving on old stacks of rice, a few dates and water from unsafe sources such as drainage ditches.
“The stories coming out of Falluja are horrifying,” Nasr Muflahi, the Iraq director for the Norwegian Refugee Council, said in a statement. “People who managed to flee speak of extreme hunger and starvation.”
To allay fears that the battle for Falluja will heighten sectarian tensions, Iraqi officials, including Mr. Abadi, and militia leaders have said they will adhere to a battle plan that calls for the militias not to participate in the assault on the city.
If the militias do hold back as promised, then the United States is likely to step up the tempo of the air campaign, as it did in the battle last year for Ramadi, the capital of Anbar Province. In that fight, Iran’s militias stayed on the sidelines.
The American military role in Iraq has been limited mostly to airstrikes and the training of the army. But, as in northern Syria, there are also Special Forces soldiers in Iraq, carrying out raids on Islamic State targets. In northern Iraq, where they work with Kurdish forces, two American Special Forces soldiers have been killed.
Iraq’s elite counterterror forces are preparing to lead the assault on Falluja; they have long worked closely with the United States and are considered among the few forces loyal to the country and not to a sect. A few thousand Sunni tribal fighters from the area are also involved in the operation.
The United States military estimates that between 500 and 1,000 Islamic State fighters remain in Falluja, and aid agencies have estimated the civilian population left in the city at 50,000 to 100,000.
A big question going into the battle is whether the Islamic State fighters will dig in and fight or, as they have in some other battles, throw away their weapons and try to melt into the civilian population.
“What we have seen is two flavors of Daesh,” said Col. Steven H. Warren, an American military spokesman in Baghdad, using an Arabic acronym for the Islamic State. In Ramadi, he said, the Islamic State fortified the city and fought for it, while in other cities of Anbar, such as Hit and Rutba, the fighters largely fled in the face of government offensives.
For the United States, there is also the matter of history: Led by the Marines, its forces fought two bloody battles for Falluja in 2004. Mindful of this past, American officials would have preferred that the Iraqis left Falluja alone for now and focused on the Islamic State stronghold of Mosul in the north.
But the battle is coming, and there are echoes of that history already. One rallying cry for the Iraqi forces is revenge for the killing, last year, of a Shiite soldier who was captured by the Islamic State, paraded through Falluja and hanged from a bridge.
If that sounds familiar, it is.
The American military’s assault on Falluja in April of 2004 was in retaliation for an episode that became an early symbol of a war spiraling out of control, the image of it as indelible as it was gruesome: the bodies of four Blackwater contractors dangling from the ironwork of a bridge.
Falih Hassan and Omar Al-Jawoshy contributed reporting from Baghdad, and Nick Cumming-Bruce from Geneva.