The operation to liberate Fallujah from the Islamic State is underway. We know how this ends. Large numbers of ISIS fighters will be killed. Fallujah will be turned to rubble; hundreds of civilians will be killed. Prospects for reconciliation will be ruined.
ISIS has administered Fallujah since 2014. The black flags of ISIS were hung by Iraq's Sunnis, not by foreign fighters. Sunnis welcomed ISIS as an alternative to the Shiite-led government in Baghdad, which marginalized the country's Sunni population and polarized the population.
The sectarian divide is deep and getting deeper. The battle for Fallujah will be borne by Popular Mobilization Forces, Shiite militias trained and equipped by Iran and under Tehran's control. The militias have a reputation for revenge-taking and bloodletting.
Fallujah won't be an easy fight. Every building is booby-trapped. The city's defenders are highly motivated. Just as US Marines fought street to street in 2004, Popular Mobilization Forces and Iraqi troops will fight for every square inch. There will be massive casualties.
Civilians will be seriously affected. Thousands are trapped in Fallujah. They lack food, water, and medical supplies. Many are starving.
Some will die from the US air bombardment or from artillery of the Iraqi Security Forces. Others will be executed by ISIS trying to escape. A few may get out. Internally displaced Sunnis are unwanted in a deeply resentful Shiite-majority country.
The pending disaster in Fallujah portends badly for Mosul, Iraq's second largest city, where ISIS is digging in for a last stand. Like Ramadi and Fallujah, Mosul may ultimately be liberated. It will, however, be turned to dust.
Liberating Fallujah is necessary. The Islamic State cannot be allowed to survive.
Yet, the battle for Fallujah will not end the ISIS occupation. It will not bring peace to Iraq or lead to reconciliation between Iraqis. Sunnis will blame Prime Minister Haider al-Abadi's scorched earth policy for their suffering. Iran will be vilified, deepening regional divisions and sectarian tensions.
Iraq can only be saved by winning the hearts and minds of Iraqis. Iraq's survival as a state depends on restoring it as a unified, multi-ethnic and mixed sectarian country, with social harmony prevailing between its communities.
This dream died long ago. Fallujah's ruin is just another nail in the coffin. The battle will be won, at great cost.
Mr. Phillips served as a senior adviser and foreign affairs expert at the U.S. Department of State during the administrations of Presidents Clinton, Bush, and Obama. Phillips was a member of the Future of Iraq Project. He is author of Losing Iraq: Inside he Post-War Reconstruction Fiasco and The Kurdish Spring: A New Map for the Middle East.