As the United States dispatches military advisers to help Iraq build a force to fight the Islamic State, often referred to as ISIS, the police of Nineveh Province, who have experience and self-interest in actually battling the jihadists, have been largely abandoned. In a region that the Islamic State now controls, lingering distrust by the Shiite-led central government has stymied efforts by provincial officials to turn the former police into a local force. The central government fears that the police officers, who are mostly Sunni, will sell their weapons to the jihadists — or join them.

The marginalization of Nineveh’s police force is one example of how the key to rebuilding Iraq may rest less in the airpower and bombing runs of the United States and its allies than in bridging the differences between the Shiite-led central government and Sunni communities. Shortly after the jihadists seized most of the province in June, the Iraqi government was so distrustful it cut off the officers’ salaries, rendering most of them destitute.

Maj. Gen. Khalid al-Hamdani, the Nineveh police chief, said more than two-thirds of the province’s 24,000 officers were trained by the United States as part of its roughly $8 billon program to strengthen Iraq’s police between 2003 and 2012. […]