In Iraq, the danger of a dormant Islamic State

Islamic State swept into northern Iraq in 2014, but the door opened for it three years earlier, when the U.S. withdrew its troops from the Middle East country. Left on their own, Iraqi troops dropped their guns and fled the onslaught.

Islamic State militants then ruled the northern city of Mosul and a host of other cities and towns with nihilistic brutality that entailed public beheadings and the use of women as sex slaves.

It took three years for Iraqi troops to regroup, and with the help of U.S. military advisers and airstrikes, retake Mosul and the rest of Islamic State-held Iraq.

Today, Mosul slowly rebuilds. The remnants of Islamic State have scattered into the desert. Game over? Hardly. Yes, Islamic State has been vanquished, but Iraq remains fertile ground for a comeback.

The U.S. and Baghdad are stepping up talks about maintaining a U.S. military presence in the country, USA Today recently reported. It’s not known how large an American contingent would be involved, but its role would likely mirror that of U.S. troops in the bid to defeat Islamic State — advising Iraqi commanders and providing surveillance and intelligence help.

James Jeffrey, a former U.S. ambassador to Iraq and now a foreign affairs analyst, told USA Today that the new contingent probably would be smaller than the current force of 5,500 soldiers.

Keeping American boots on the ground in a part of the world as unstable as Iraq is never an easy decision, but it behooves both Iraq and the U.S. to hammer out a deal. Iraq’s peace is desperately fragile. Shiite-led Baghdad continues to marginalize the country’s Sunni minority, leaving the nation vulnerable to a resurgence of Sunni-led militancy down the road. Islamist insurgencies have a way of lying low and flaring up when the time and circumstances are ripe.

And consider this: Islamic State doesn’t need a caliphate to maintain its online appeal to lone wolves, like the Uzbek immigrant who killed eight people in Manhattan in a truck attack on Halloween, or the Bangladeshi who tried to blow himself up in a crowded New York subway station Dec. 11.

An American military intelligence presence is needed in Iraq to ferret out and neutralize whatever Islamic State is up to, whether that be web propaganda or suicide bomb attacks in Baghdad. Though Islamic State is beaten in Iraq, “the fight is not over,” Defense Secretary James Mattis said in November. “Even without a physical caliphate, ISIS remains a threat to stability in the recently liberated areas, as well as in our homelands.”

Just as important: A continued American military presence in Iraq, even if smaller than the force there now, also serves as a counterpoint to Iran, which strives for the day when Iraq becomes its proxy state.

Though both Iraq and the U.S. paid a stiff price for the pullout of American troops in 2011, the Obama administration didn’t have much choice. Barack Obama tried to negotiate a deal to keep a contingent of American soldiers there, but Baghdad refused. Opinions vary on whether Obama might have tried harder. But the country’s parliament balked at giving U.S. troops legal protection from Iraqi courts, a condition Obama was right not to accept.

Obama was late, however, in realizing the gravity of the Islamic State threat, at one point shrugging off the terror group as “junior varsity.” He later changed course.

Neither the U.S. nor Iraq can afford to again underestimate Islamic State and its bloodlust determination to sow destruction and chaos.

A small, focused contingent of American troops can help serve as a firewall to that determination.