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ISIS will lose Mosul and Raqqa. What happens next?

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The jihadists of the Islamic State are finally being driven out of their two main bastions: The northern Iraqi city of Mosul and the eastern Syrian city of Raqqa. For some three years, their ability to control these two urban centers, particularly Mosul, served as warped validation of their ambitions to build a modern-day caliphate.

Now, after months of airstrikes and a prolonged U.S.-backed offensive, the jihadists are in retreat. Last week, Iraqi Prime Minister Haider al-Abadi hailed the recapture of Mosul's historic Great Mosque of al-Nuri, which had been tragically reduced to rubble by the militants, as the "end" of the jihadists' "state of falsehood." It was from that site in 2014 that the Islamic State declared the advent of its caliphate. Iraqi forces are in what seems the final stages of an intense house-by-house battle to reclaim the last streets of the city still occupied by the militants.

On Tuesday, U.S. authorities announced that their allies on the ground in Syria — the Kurdish-dominated Syrian Democratic Forces, or SDF — had breached a wall surrounding Raqqa's Old City after "overcoming heavy ISIS resistance." After months of relentless airstrikes on the city, the Islamic State's fighters in Raqqa now must face their enemy in the streets.

Brett McGurk, the top U.S. civilian official coordinating the fight against the Islamic State, hailed the moment as a "key milestone" in the "campaign to liberate the city."

But even if the Islamic State is losing, nobody ought to rest on their laurels. Countless civilians remain vulnerable and in need of aid, at risk of hunger and disease as well as the violent reprisals of militants. In Mosul, dozens, perhaps hundreds, have perished amid coalition airstrikes.

"Civilians escaping right now speak of horrific experiences. They have been caught between aerial bombardment, artillery, snipers and car bombs. They live in fear; they hide in their homes without food or water," said Iolanda Jaquemet, a spokeswoman for the International Committee of the Red Cross, to my colleagues.

In Raqqa, too, hundreds of thousands of people are caught in the crossfire, with casualty numbers rising as a result of airstrikes as well as sniper fire and brutal executions carried out by the jihadists to intimidate those still trapped in the city.

In this context of violence and trauma, securing peace will be far harder than winning the war. A new report from the Combating Terrorism Center at West Point emphasized "the importance of post-liberation security, governance, and politics." It tracked hundreds of attacks launched by the Islamic State in areas where they had supposedly already been driven out, noting the persistence of militant cells in cities "liberated" from their rule.

"Simply pushing the Islamic State out of a formal governing position in Iraq and Syria, while an important first step, will not ensure the achievement of these post-liberation tasks and reduce the likelihood that the Islamic State or some other terrorist organization emerges to take advantage of a tenuous peace," wrote the report's authors, Daniel Milton and Muhammad al-Ubaydi.

This is where things really get complicated. In Iraq, Mosul's "liberation" is only the first act in a tense drama unfolding in the country's north, where the Shiite-dominated government in Baghdad will struggle to reassert control. The Iraqi Kurds, crucial to the battle against the Islamic State, are now pushing for an independence referendum in their autonomous region. Local Sunnis remain distrustful of — if not outright hostile to — a number of Iranian-backed militias that have helped fill the security vacuum.

"Much of the battle against ISIS has taken place in a region that has been fought over ever since oil was found in Kirkuk in the 1930s," wrote Joost Hiltermann of the International Crisis Group. "The deeper conflicts here — between Arabs and Kurds, between Shia and Sunni, between neighboring powers such as Iran and Turkey, and among the Kurds themselves — will only escalate as the victors, fortified by weapons supplies and military training provided by foreign governments, engage in a mad scramble for the spoils."

The Raqqa campaign, too, is shaped by geopolitical complexity. The SDF, backed by the United States, is reviled by Turkey for its connections to the outlawed PKK, a Kurdish separatist group that both Ankara and Washington deem a terrorist organization. My colleague Alice Martins recently journeyed with a detachment of SDF fighters to the Raqqa front.

"Some of the commanders I met appeared to have a more direct connection to the PKK, speaking with a Turkish accent or else refusing to say where they were from," wrote Martins. "Often, they did not know the names of the villages or neighborhoods where they were fighting."

In Washington, civilian and military planners are already preparing for the next stage of the war in Syria. It looks, as my colleague Karen DeYoung wrote, to be "a complex fight that will bring them into direct conflict with Syrian government and Iranian forces contesting control of a vast desert stretch in the eastern part of the country."

Clashes have already taken place, with the U.S. shooting down drones used by Iranian-backed militias. The risk of an escalating American military commitment in Syria, potentially locked in conflict with the regime of Syrian President Bashar al-Assad — something the Obama administration tried to avoid — now seems more of a reality under President Trump.

Still, there appears to be a divide between the White House and officials in the Pentagon, the latter eager to avoid getting sucked into the Syrian war and the prospect of removing Assad. The widespread chaos and uncertainty is its own kind of valediction for the Islamic State.

"The fact is that, although ISIS’s audacious ultraviolence ultimately set the scene for its material undoing, it also meant that it could work towards creating the world it wanted to inhabit — a polarized, turbulent place that accommodated the jihadist ideology uncannily well," wrote Charlie Winter of the International Center for the Study of Radicalization in London.

In this current environment, the root causes that led to the emergence of the Islamic State — political turmoil, sectarian tensions and shoddy governance — won't be getting addressed any time soon.

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