The Islamic State of Iraq and al-Sham (ISIS) is starting to show some wear and tear. True, it pulled off the gruesome execution of Jordanian pilot Moaz al-Kasasbeh; true, it has attracted jihadists from across the world; and true, it still holds swaths of Iraq and Syria. But cracks are appearing in the self-styled Caliphate.

One reason is that, starting in the late summer, the U.S. intervention in Iraq helped stall the ISIS advance. Since then, troops have been able to go on the offensive and start expelling the terrorist group from the territory it holds; it has already lost Kobani, the north Syrian border town where much of the violence is centered, and has also suffered significant defeats in Bajyi, Jurf al-Sakhar, Diyala, and the Mosul Dam. In the grand scheme of things, this does not translate into much: Of the 55,000 square kilometres of territory ISIS controls, it has lost only 700—around one percent. But at least the momentum has been checked. 

Now, a planned spring offensive, a joint U.S.-Iraqi effort to retake the Sunni capital of Mosul, could be a watershed moment. Iraqi Security Forces, Kurdish Peshmerga troops, and Sunni tribes—backed by U.S. air support and military advisers—will look to end ISIS’ reign in the north and west Iraq, restoring government leadership in local towns and cities.

There are risks in this strategy. ISIS finds it easiest to take over Sunni areas where there is a looming threat of Shia or Pershmerga involvement. To retake Mosul, then, the coalition will have to avoid sending Peshmerga and Shia militias into the fray. The further these forces penetrate the Sunni enclave of Mosul, the likelier they are to push Sunnis into armed resistance.

Absent any Shia or Pershmerga threat to exploit, ISIS quickly loses tactical alliances, such as the Ansar al-Sunna, Army of the Men of the Naqshbandiyah Order (JRTN), and the 1920 Revolutionary Brigades. And when it fights alone, it loses. For example, ISIS had no allies to help it secure Kobani and the Mosul Dam. In both cases, a determined Iraqi ground force supported by U.S. weaponry and airstrikes defeated ISIS, a blow to its status as a formidable terrorist army.

These are not the only setbacks that ISIS has suffered recently. According to group spokespeople and media reports, there have been at least two different coup attempts against the ISIS leadership. Back in November, ISIS announced that it had thwarted a plot by a cell of Azerbaijanis who were plotting to kill ISIS members and encourage others to join an anti-ISIS faction. In recent days, details of a coup attempt against ISIS leadership in eastern Syria, led by Abu Ayyub al-Ansari, ISIS’ governor in Raqqa, have emerged. Ansari and dozens of others were killed in response, and some of Ansari’s fellow conspirators are thought to have fled Raqqa.

Furthermore, there seems to be a sense of growing disillusionment among recruits. The level of violence is extraordinarily high, even for a jihadist group. Outside the beheadings and burnings, prisoners are pushed off buildings, crucified, buried alive, and impaled. Female recruits are being coerced into ISIS sex camps and raped. According to one United Nations committee, the group is also torturing, crucifying, and burying children alive.

Meanwhile, foreign fighters, many of whom signed on to fight the Bashar al-Assad regime in Syria, have been pushed into conflict against other armed factions in Syria. Others are given menial tasks such as cleaning weapons and transporting dead bodies from the front line. Those who refuse their duties risk being labelled apostates and killed; and those who try to escape are equally likely to die. According to the Syrian Observatory for Human Rights, over 100 people who wished to leave the ISIS were executed between October and December 2014. This suggests that ISIS is increasingly turning on itself.

Something else that is slowing ISIS down: the group has been forced to govern the land that it currently holds. And it isn’t going well. Wheat production has collapsed and electricity is sporadic. Hospital staff has fled and pharmaceutical supplies are in short supply. Water service was better under Assad and Iraq’s former Prime Minister Nouri al-Maliki. ISIS may hold territory and enforce law and order, but it is clearly not governing.

Under these circumstances, the execution of Kasasbeh was a strategic error. It has—for now, at least—outraged Jordan. The last time the country suffered such a high-profile attack was in November 2005, when al Qaeda in Iraq killed 60 people in three coordinated attacks against hotels in Amman. This act not only cost the group a large amount of support across the region, it also led Jordan to ramp up its intelligence gathering. Within months, al Qaeda in Iraq’s Jordanian leader, Abu Musab al-Zarqawi, was killed in a mission to which Jordanian intelligence had made a key contribution. If Jordan does the same this time, it will come at a time when ISIS can barely afford it.

On the other hand, the gains that Iraq and the West have made against ISIS are reversible if there is insufficient international will to press them home. It is critical that the United States stays engaged militarily. And partner nations, such as the United Kingdom, must increase support in order to share this burden.

It is also vital to recognize that, ultimately, only the Sunnis can clear their areas of ISIS’ presence. One of the main reasons Iraqi security forces fled Mosul in June 2014 was that they had no political and economic ties there, and so were not interested in fighting and dying for it. The Sunnis are, provided that ISIS cannot convincingly argue that it is the sole protector against the Shia.

And that is why it is counterproductive for the United States to work alongside Iranian-backed militias against ISIS. The West cannot back Sunnis into a corner by offering them the choice of conflict with Shia militias—with the sectarian bloodletting that would surely follow—or an alliance with ISIS. A comprehensive U.S.-led strategy must involve partnering with Sunnis in fighting ISIS and reassuring Sunnis that there will be no Shia death squads after ISIS’ defeat.

ISIS is on the run, but current U.S. policy isn’t taking full advantage of that. Now is the time. If the West addresses deficiencies in its own strategy, weaknesses in ISIS’ own framework will cause the group’s downfall.

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