BAGHDAD >> The U.S.-led coalition has come under increasing scrutiny by monitoring groups regarding civilian casualties in the fight against the Islamic State group in Iraq, a turn that is worrying some in the country’s political leadership who fear the destruction and loss of life could complicate hopes of reconciliation with the country’s minority Sunnis.

The Pentagon acknowledged over the weekend that at least 352 civilians have been killed by coalition strikes in Iraq and Syria since the start of the air campaign against IS in 2014. However, activists and monitoring groups say the number is much higher.

The coalition argues that casualties are inevitable in urban warfare with irregulars mixing with civilians and determined to stage a last stand. But critics see a degree of recklessness and excess that aligns with the heavy-handed rule of the Sunni areas by the Shiite dominated Iraqi government.

Here’s a look at some aspects of the situation.

A devastating mistake

Last month, the Pentagon launched an investigation into an incident in which Mosul residents say a single airstrike killed more than 100 civilians sheltering in a house in the western part of the Iraqi city that was also being used by IS fighters.

While both Iraqi and coalition planes are active in the skies above Mosul, the U.S. acknowledged coalition planes conducted a strike “at the location corresponding to allegations of civilian casualties,” but did not confirm the number of casualties inflicted or the circumstances of the event.

The incident sparked outrage in Iraq and beyond with calls from local government officials as well as the United Nations for greater restraint in the fight against IS for Mosul.

Despite the allegations surrounding the March 17 strike, the spokesman for the U.S.-led coalition Col. John Dorrian told The Associated Press that the coalition’s anti-IS operations remain “the most precise air campaign in history.”

“But all the tactics, techniques and procedures and plans that we have, all these things are executed by people,” he said, “and what that means is, it’s not going to be perfect, it’s going to be as good as we can possibly make it.”

More than a month since the incident, Dorrian declined to specify when the investigation — the most extensive single investigation into civilian deaths undertaken by the coalition since the fight against IS began — would be complete.

Why it’s happening

Civilian deaths in the nearly three-year battle against IS spiked as Iraqi forces pushed into Mosul, undertaking some of the toughest fighting yet. The battle space, with its narrow streets, is claustrophobic and the Islamic State group is holding hundreds of thousands of civilians in the city as human shields.

Since Iraqi forces pushed into western Mosul in February, the fighting has killed and wounded more than 4,000 civilians, according to the United Nations, a number that only counts civilians who reached a trauma hospital for treatment.

In the most recent report, the Pentagon announced on Sunday that investigations conducted during the month of March show that coalition airstrikes killed 45 civilians, mostly in and around Mosul. In each incident, the Pentagon said “all feasible precautions were taken,” but the strikes still resulted in “unintentional” loss of civilian life.

The report came days after President Donald Trump gave the Pentagon greater flexibility to determine the number of U.S. troops in Iraq and Syria. The Pentagon had already been making quiet, incremental additions to the troop levels in both countries in recent months.

A look at the numbers

The Pentagon acknowledged over the weekend that at least 352 civilians have been killed by coalition strikes in Iraq and Syria since the start of the air campaign against IS. Activists and monitoring groups put the number much higher, with London-based monitoring group Airwars reporting coalition strikes have killed more than 3,000 civilians in Iraq and Syria since 2014.

The Pentagon’s Sunday statement also included the findings of an audit begun in March that inspected the way the U.S.-led coalition reports and tracks civilian casualties in the fight against IS.

The statement said the audit found that 80 civilian deaths caused by coalition airstrikes had not been previously publicly reported and two civilian deaths previously reported were found to have not been caused by the coalition.

Some in Iraq’s political leadership have expressed concern that the levels of damage and loss of human life in Mosul will make reconciliation with the country’s minority Sunni population more difficult after a military defeat of IS.

What it means for post-war governance

Iraq’s Parliament speaker, Salim al-Jabouri, one of the highest ranking Sunni government officials, has said that reports of increased civilian casualties in western Mosul are of “great concern.”

When Haider al-Abadi took office in 2014, he promised reforms that would hold corrupt Iraqi leadership accountable and allocate more of a political stake to the country’s Sunnis. Al-Abadi has handed more control over to Iraq’s regional leadership and appointed a Sunni to lead the Ministry of Defense. But some Iraqis are warning the outcome of the Mosul operation could be pivotal for how the country’s Sunnis view Baghdad’s Shiite-dominated government.

Iraq’s foreign minister has warned such a massive reconciliation effort will need funding and support akin to the Marshall Plan that helped western Europe recover from the devastation of World War II.

In order for Iraq’s military gains to stick, the international community needs “to present assistance to Iraqis and support development and overcome the effect of war against Daesh terrorist gangs,” Jaafari said in a statement released by his office. Daesh is an Arabic name for IS.

Roots of IS support

When the Islamic State group rampaged through northwestern Iraq in 2014, the extremists were welcomed by some Sunnis who thought IS represented a Sunni revolution that would deliver them from the country’s Shiite-dominated government in Baghdad.

Under former Prime Minister Nouri al-Maliki, many of Iraq’s Sunnis began to view the country’s security forces as an occupying force. Police and military units often swept through Sunni communities detaining all military-aged males in an attempt to quell dissent, filling the country’s prisons with men arrested on trumped-up terrorism charges.

Baghdad has not yet presented a comprehensive plan for the governance of Nineveh province once the fight for Mosul is concluded and plans for an Iraqi “national guard” that would give greater control of local security to regional leaders have languished in Parliament.

The United Nations reports more than 800,000 civilians have returned to Anbar province after much of that territory was retaken from IS last year, but rebuilding there is mostly being financed with private money as Iraq is still battling an economic crisis sparked in part by the worldwide drop in oil prices.