Iraq’s parliament approved a new government with Kurdish and Sunni deputy prime ministers on Monday, ending weeks of gridlock that enabled the militant group that calls itself the Islamic State to rout the Iraqi army and conquer large swaths of territory in the northwest and across the border with neighboring Syria. But reprisals from Kurdish and Shia militants against Sunnis who supported the Islamic State could doom an attempt at reconciliation.

Meeting his constitutional deadline, Prime Minister Haider al-Abadi got parliamentary approval for his ministers, many of whom are Shia like him. However, the government also includes Sunni Arabs and Kurds in effort to draw both sects back into the political process.

The exclusion of especially Iraq’s Sunnis under Adabi’s predecessor, Nouri al-Maliki, convinced many to support, or at least acquiesce in, the Islamic State’s uprising.

The group, an Al Qaeda offshoot, has proclaimed a caliphate in the territory it controls, spanning the northeast of Syria — where it also battles the regime of President Bashar al-Assad — and the west of Iraq.

The militants’ brutality — they have massacred hundreds, if not thousands, of nonbelievers — prompted American intervention last month. The United States have carried out dozens of airstrikes against Islamic State targets, enabling Kurdish paramilitary forces and Shia militias to regain ground. President Barack Obama said on Sunday they will ultimately “defeat” the insurgents.

But the airstrikes may have also given the Kurds and Shia the upper hand in a sectarian struggle. The Reuters news agency reports that “the aftermath illustrates the unintended consequences of the American air campaign.” Sunni Muslims who fled the violence are prevented from returning home. Some have had their houses pillaged and torched.

Reuters warns that the fallout risks worsening grievances that helped the Islamic State find support among Iraq’s Sunnis. “That may make it more difficult to bring Sunnis on side and convince them to fight the militants.”