BAGHDAD — As Iraqi forces push to reclaim Mosul from the Islamic State, U.S. and Iraqi officials are bracing for what they expect will come after the terrorist group loses its last major urban stronghold: a long and bloody insurgency.
The Islamic State's suicide attack in Baghdad that killed nearly 330 people this month, U.S. diplomats and commanders say, is a foreshadowing of the violence the group will unleash as its territory in Iraq and Syria shrinks, and as it reverts to its guerrilla roots. That transition will not be complete until after the military campaign for Mosul has succeeded, and the start of that dauntingly complex operation is still months away. But already, officials say, many Islamic State fighters who lost battles in Fallujah and Ramadi have blended back into the largely Sunni civilian populations there, and are biding their time to conduct future terrorist attacks.
And with few signs that the beleaguered Iraqi prime minister, Haider al-Abadi, can effectively forge an inclusive partnership with Sunnis, many senior U.S. officials warn that a military victory in Mosul will not be sufficient to stave off a lethal insurgency. Two years ago, the Islamic State, also known as ISIS, exploited Sunni alienation from the Shiite-led government when it seized wide portions of the country's west and north.
"To defeat an insurgency, Iraq would need to move forward on its political and economic reform agenda," Lt. Gen. Sean B. MacFarland, the top U.S. commander in Iraq, said in an email.
A sustained insurgency in Iraq, while the United States and its allies still combat ISIS in Syria, would also pose one of the first major challenges to the next U.S. president, who will take office in January. U.S. public opinion has so far supported President Barack Obama's deployment of roughly 5,000 troops to help Iraq reclaim territory it lost to ISIS in 2014, but it is not clear whether political support would dissipate in a sustained effort to fight insurgents.