The fall of the ISIS ‘caliphate’

Dr Leah Farrall, Foreign Affairs, Defence and Security

Key issue
Although the fall of the ISIS ‘caliphate’ has lessened the threat it poses to Iraq and Syria, the organisation has not been vanquished. Complex challenges remain, and sustained international efforts are required to ensure it cannot resurge in either country.


In March 2019 the Islamic State of Iraq and al-Sham (ISIS) was ousted from the last of the territory it had seized across Syria and Iraq. At its late 2014 peak, ISIS controlled large swathes of both countries, subsuming government resources and bureaucracy—along with industry, commerce, and agriculture. Millions of Syrians and Iraqis were forced to live and work under ISIS’s brutal rule and its extortive taxation regime, via which it generated the bulk of its income.

ISIS systematically and violently targeted non-Sunni Syrians and Iraqis, expelling them from their homes, plundering their properties and businesses and claiming them as a war spoil (ghanima). Non-Muslim minorities were forced to pay a form of protection tax (jizya), or convert on threat of death. Thousands were taken hostage, ransomed, or executed, while others were enslaved.

ISIS attracted unprecedented numbers of foreigners who came to join the organisation or live in territory under its rule. Estimates place the total number at 40,000 people from 80 countries. The number of Australians who travelled to Iraq and Syria has been reported to be 230, although this figure includes people who joined other militant groups.

As a territorially expansive organisation, ISIS has sought to co-opt conflicts and grow subsidiaries in other parts of the world, including elsewhere in the Middle East, Africa, the Caucasus, South Asia, and Southeast Asia. Subsidiaries are sometimes existing insurgent groups ISIS subsumed, or splinter factions of them. Their relationships with ISIS vary in closeness, depending on the nature of ties between them.

Further reflecting the importance ISIS places on territory, subsidiaries are treated as, and organised by, provinces (wilayat). Because ISIS rejects the legitimacy of international borders, a province(wilayah)may stretch across several countries. There can also be multiple provinceswithin a country. ISIS has also referred toareas where it has neither territory nor an announced subsidiary as provinces. ISIS does so to maintain an appearance of expansion—as was the case with its April 2019 reference to ‘wilayah Turkey’, following the loss of its last territory. Expansion of territory has not, however, been ISIS’s sole focus.

ISIS had already set up an external operations section dedicated to organising terrorist attacks outside Syria and Iraq before it declared the establishment of its caliphate in mid-2014. The section was part of the external wing of ISIS’s security department. It was established as a means of exerting control over foreigners within ISIS who were agitating to carry out external attacks. The security department’s internal wing was already holding Western hostages.

In September 2014, the head of ISIS’s security department released a statement that was akin to a standing operational order and which has become one of its most enduring and important releases. Although framed as a response to growing international efforts against ISIS, the statement was driven by internal imperatives to co-opt the jihadist milieu and project an image of power and capability. The statement gave ISIS supporters around the world, particularly in the West, carte blanche sanction to carry out attacks in its name. Supporters were told they should attack wherever and whenever they could, without seeking further permission or instruction. Australia was among several countries singled out.

Almost immediately, ISIS supporters in a number of Western countries began to follow this guidance, carrying out what came to be termed ‘ISIS inspired’ or ‘lone-actor’ attacks. Their attacks served to amplify ISIS’s terrorist reach beyond what its external operations section could direct. The widening of the threat ISIS posed was reflected by 80 countries joining the Global Coalition Against Daesh following its establishment in September 2014. The US leads the military component of the coalition under the auspices of Operation Inherent Resolve (OIR).

OIR grew to ‘encompass the efforts of more than sixty coalition partners’ involved in providing support to ‘Iraqi Security Forces and Syrian opposition groups’ in their fight against ISIS. Australia has been an active partner via Operation Okra. It has also contributed personnel to Operation Gallant Phoenix, a fusion cell of ‘over 250 people representing more than 25 nations’ that collects and analyses intelligence relating to foreign fighters.

It took close to five years of fighting and over ‘34,000 air and artillery strikes’, which destroyed cities and displaced millions of people, to expel ISIS from the territory it held in Iraq and Syria. Yet, in early 2019, when it was already clear ISIS would lose its last enclave in Baghuz, Syria, the US Intelligence Community warned that it continued to pose a threat, noting ISIS still had eight provinces, ‘more than a dozen networks, and thousands of dispersed supporters around the world’.

A similar assessment was provided to the United Nations Security Council in the Secretary General’s report on the threat ISIS posed to international peace and security. This report also detailed how ISIS remained active in Syria and Iraq and cautioned that it was attempting to rebuild. Around the same time, US military officials told the OIR Lead Inspector-General that ‘ISIS is regenerating key functions and capabilities more quickly in Iraq than Syria’, and noted that without ‘sustained pressure’ it could also regain limited territory in Syria within twelve months.

These assessments collectively made clear ISIS was far from vanquished in either Syria or Iraq, and without ongoing efforts against it, was likely to resurge. ISIS leader Abu Bakr al-Baghdadi certainly telegraphed his intent in April 2019 for the organisation to do so, less than a month after Baghuz fell, and with it, his caliphate. He called for ISIS to follow a strategy of attrition in its path to resurgence—the same broad strategy used by the organisation to rebuild after its near defeat in Iraq a decade earlier.

Following al-Baghdadi’s speech, ISIS provided further explanation of this strategy and additional tactical guidance in its Al-Naba newsletter. Although a range of factors contributed to ISIS’s rise to establish a caliphate in 2014, it clearly believes the rebuilding strategies put in place following the 2008 ‘decimation’ of its Iraq insurgency were key to its success, and will work again.

How ISIS previously resurged

After its near defeat in 2008, ISIS—then known as the Islamic State of Iraq (ISI), was forced into clandestine mode and ‘began to plot its return’. In order to preserve its remaining membership ISI devolved its organisational structure to operate more like a network, but one that was functionally ordered. It was still operating in this mode when Abu Bakr al-Baghdadi took the helm in 2010. He did so at a time when ISI had suffered significant losses, and amid its sustained assassination campaign against Sunnis who had helped crush the insurgency.

Membership replenishment strategies ISI pursued at that time included the recruitment of paroled prisoners, and later, in its 2012–2013 ‘Breaking the Walls’ campaign, undertaking a series of jailbreaks. These were followed in mid-late 2013 by ‘Soldier’s Harvest’, a campaign of infiltration, intimidation, and targeted assassination of Iraq’s security forces and Sunnis working with them. It also involved inciting sectarian strife in an attempt to create chronic instability.

‘Soldier’s Harvest’ is one manifestation of ISI’s broader attrition strategy at that time, but it was not the only element. Through several campaigns ISI used a wide range of insurgency tactics in its efforts to exhaust security forces and increase the group’s power. This was done with the aim of growing strong enough to seize and hold territory, and ultimately, expanding to establish an Islamic State.

When ISI was still operating as a cellular network, with limited numbers and resources, its options were limited. Hit and run tactics were possible in areas near to where it had retreated, while hit, hold and run tactics initially were not. ISI began with hit and run attacks, mostly in remote rural areas where security was weak. Raids, typically at night, were used to assassinate village heads or tribal leaders, or to destroy crops, houses, or local infrastructure. Roads were also targeted. These types of attacks aimed to exacerbate existing security weaknesses to expand ISI’s strength in that area and to cause communities to lose trust in the ability of security forces to protect them. Extortion, kidnappings and other mafia-like activities were used to rebuild finances.

As it grew stronger ISIS also targeted the outposts and bases of security forces. This marked a transition from mostly hit and run attacks, to hit, hold and run. Small villages and bases were attacked and held for short periods of time, for purposes such as looting weaponry, massacring security forces or destroying infrastructure. Once these were achieved, fighters withdrew. ISI’s March 2012 raid on a police complex in Haditha clearly highlighted its growing ability to carry out such attacks. Over 90 fighters attacked the complex and held it long enough to execute 25 policemen, loot weaponry, and film the entire episode.

These types of attacks were expansive in nature, targeting new areas to weaken security, rather than targeting areas where security was already weak. They also required more resources than for simple hit and run raids such as a location in which to train and to which to return to store loot. Their purpose was to demonstrate ISI’s growing reach and the security forces’ impotence. To further amplify ISI power, attacks were filmed and used in propaganda. By early 2013, ISI had grown in size and capabilities, carrying out hit, hold and run attacks in a growing insurgency across a number of provinces in Iraq. But it still lacked territory.

Gaining access to sanctuary, resources, and ultimately territory in Syria had a decisive impact on ISIS’s fortunes. It was not a chance occurrence, rather the culmination of an expansion plan that involved attempting to co-opt the Syrian conflict and other rebel groups, a strategy ISIS has since attempted to replicate elsewhere. Shortly after the Syrian conflict began in 2011, al-Baghdadi dispatched senior operatives to the country to establish a presence. The group they started, Jabhat al-Nusra, grew rapidly, fuelled by ISI money and its old Syrian logistics networks. By the end of 2012, it was a key player in the Syrian rebel milieu, supported by a growing foreign fighter contingent and increasing numbers of ISI members coming from Iraq after being freed in jailbreaks. In March 2013 al-Nusra fighters, alongside other rebel groups, seized the Syrian city of Raqqa.

The following month, Abu Bakr al-Baghdadi relocated to Syria and attempted to reassert control over al-Nusra, effectively ordering its members to disband and merge back into ISI to become the Islamic State of Iraq and al-Sham (ISIS). An acrimonious split between the two groups followed, with al-Nusra’s leadership refusing to disband or relinquish control of territory it held, including Raqqa. However, many fighters in al-Nusra’s ranks, including most Iraqis and foreigners, ultimately left to join ISIS. In January 2014, following months of inter-group conflict, ISIS took full control of Raqqa.

By then, ISIS’s Iraq-based campaigns to target and exhaust security forces were gaining momentum, supported by an influx of fighters, money and resources from Syria. A sophisticated propaganda effort was also underway. It is alleged to have contributed to the mass desertion of Iraqi security forces from Mosul in June 2014 as ISIS fighters approached, despite vastly outnumbering them.

The size and speed of the desertions caught ISIS by surprise. In an April 2019 article explaining tactics to use in support of its attrition strategy, ISIS admitted its leaders had not intended to seize all of Mosul. The initial plan was to take a part of the city ‘for several hours’ in a hit, hold and run attack on a jail, in order to ‘to swell its ranks’. However, the mass desertions led ISIS leaders to decide they could take the city. Within a matter of days, ISIS was in full control of Mosul, Iraq’s second largest city.

ISIS in power

Once in power, ISIS set about presenting itself as an effective source of alternative governance and stability. In its early stages ISIS outperformed some bureaucracies it subsumed, providing services such as garbage collection, electricity, and community policing that were previously absent or subject to corruption and mismanagement. This allegedly earned ISIS an initial modicum of support for its rule in certain areas.

The provision of such services also came at a significant cost to liberty in the growing territory over which ISIS ruled. Public servants were forced to work for and swear allegiance to ISIS on threat of punishment or death. Other infringements to liberty ranged from conscription for military activities and restricting movements within and between cities, to controlling communications. Internet access was banned in private homes, with people told to instead go to internet cafes where use could be better monitored, while in some places mobile phones were banned.

ISIS also rapidly issued rules dictating social interactions and conduct, gender relations, and personal grooming and dress, which were imposed by its public morality enforcement (hisba)department. For locals who did not support ISIS, and who were unable to flee before it seized power, there was no choice but to follow the new rules, which were most zealously enforced by foreign members of ISIS’s hisba brigades. Both male and female foreigners worked in hisba brigades. Foreigners were valued for this work not only because they were zealous enforcers with a reputation for brutality, but also because they had fewer ties to local communities, which is why they also performed the role of executioners. Although hisba brigades provided an important and wide-ranging social control function for ISIS, true power lay with its intelligence body, the security department.

An intelligence state

ISIS’s security department was omnipotent across the organisation and played an essential role in its resurgence, growing more powerful as ISIS gained territory. ISIS’s external security wing ran several sections, most operating in network form with both functional and personnel overlaps. The wing recruited for and organised external terrorist attacks, arranged external travel, and undertook document forgery. It administered international procurement and logistics networks, with responsibility for sourcing items such as counter surveillance technology and drones. The wing oversaw information technology and external communications, including to other provinces. It also oversighted ISIS media productions in coordination with the internal wing.

ISIS’s internal security wing was its most powerful body, effectively performing the role of a domestic intelligence service. It identified infiltrators, spies, informants and seditious elements within ISIS and its territory. Known for its brutality and torture, the wing was staffed with a number of former Iraqi and Syrian officials. They also recruited, trained and ran a covert paramilitary squad, which conducted terrorist attacks inside Iraq and Syria, carrying out bombing campaigns, targeted assassinations and kidnappings.

Some of the earliest signs ISIS was experiencing internal schisms and beginning to weaken came from the changing behaviour and roles of its security department. By late 2014, as airstrikes began to take their toll, the internal wing reportedly became more paranoid, with reports of people being randomly seized off the street on suspicion of being infiltrators. In 2015 as pressure on ISIS grew from military actions against it and a significant loss of revenue, the external security wing began to informally encourage people seeking to join the caliphate to emigrate to Libya, which was followed later by a formal announcement by al-Baghdadi. Meanwhile, both internal and external wings began to relocate and disperse key resources, first their own and then those of ISIS more broadly.

Key members were sent away from areas thought vulnerable to attack; some were sent to external provinces and outside countries. This process gained more urgency as territorial losses accrued and cadres and cash reserves were lost in airstrikes. The internal wing was also heavily involved in efforts to quash an ongoing ideological rift within ISIS that had grown in severity, threatening to destabilise its leadership apparatus. Under the auspices of the internal wing a special committee was established to ‘investigate’ religious figures. In reality its function was to supress dissent, which was achieved by the jailing and execution of religious figures deemed a threat to ISIS’s leadership. Establishing the committee extended the security department’s authority into an area traditionally beyond its purview, and effectively made ISIS’s religious and law-making bodies subservient to its intelligence apparatus. Some senior religious figures escaped; they were among a growing tide of people trying to leave ISIS and its territory, which the internal security wing was working to prevent.

Leaving ISIS or its territory without permission was treated as apostasy and punishable by death. Name registries maintained by the internal wing were given to checkpoints to prevent escape, leaving the use of smugglers or crossing frontlines as the only way out. The wing had prevention mechanisms in place, such as paying off smugglers to report would-be-escapees. Foreign fighters, less able to escape and blend into local populations, were used at fronts to prevent locals from attempting to ‘negotiate’ their way out and cross frontlines. ISIS fighters also held local populations hostage, using them as human shields. These tactics were used in a number of towns and cities as the caliphate slowly collapsed, including in its final enclave in Baghuz, Syria.

A new resurgence?

In both Syria and Iraq ISIS has pivoted back to a cellular operating structure and remains highly reliant on its security apparatus, whose role broadened as the caliphate collapsed. It possibly still has information about millions of Iraqis, which would assist in extortion efforts as well as targeted kidnappings and assassinations.

An estimated 14,000–18,000 ISIS remnants are thought to remain ‘under its control’ in both countries. Some 3,000 of them are reportedly ‘armed’ fighters operating in Iraq, most likely in the provinces of Anbar, Ninawa, Diyala, Salah al-Din and Kirkuk—where by late 2018 the insurgency had returned to its ‘2013 levels’ of activity.

Tactics being used come straight from ISIS’s attrition strategy playbook. Predominantly Sunni rural communities in isolated areas are being targeted; local leaders assassinated, crops burned, local farming infrastructure destroyed and farmers murdered. Outposts of Iraqi security forces are being attacked and overrun, roadside ambushes and bombings are on the increase, and ISIS is succeeding in its attempts at ‘successfully intimidating the security forces to remain within their bases at night’, further exposing local civilians to ISIS attacks and reducing trust in government forces. While most attacks in these areas have been of the hit and run variety, some have grown to be hit, hold and run, and it is clear ISIS is actively pursuing its strategy. ISIS may also benefit from the resources its security department dispersed in areas of safe sanctuary, such as those reported in the Hamrin region, where tunnel complexes and weapons stores have allegedly been found.

Stabilisation efforts are also falling short. Significant numbers of Iraqis remain internally displaced and some cities destroyed in the battle to oust ISIS still lack basic services. Donor fatigue is also an issue with only US$33 billion of an estimated US$88 billion needed by Iraq raised at a 2018 conference.

Meanwhile, rising sectarian tensions and retributive violence by state and non-state actors are creating favourable conditions for ISIS. Iraq’s government has come under criticism for arbitrary arrests and poor judicial processes. As one study noted, when ISIS ‘retreated from Iraqi territory in 2017, it left behind a population that Iraqi authorities now overwhelming regard as complicit in terrorism’. Thousands of ISIS fighters remain in custody in Iraq, among them 1,000 foreigners, including Australians.

In Syria’s northeast, the site of ISIS’s last stand, a low-level ISIS insurgency continues against Syrian Democratic Forces (SDF), a US-backed Kurdish and Arab militia in control of territory in the Middle Euphrates River Valley. The area is also a flashpoint for geopolitical tension. After US President Donald Trump’s December 2018 declaration of ‘victory’ against ISIS and announcement that US troops supporting SDF forces would be withdrawn, the Turkish Government, which does not want a permanent Kurdish presence in the region seeing ‘the autonomy-minded Kurds as a dangerous enemy’, then threatened to invade Syria. Meanwhile, the Syrian regime, backed by ‘Russian airpower and Iranian manpower’ is seeking to ‘retake’ control of this area.

The SDF holds a reported 8,000 ISIS fighters in Syria’s northeast. They also hold over 1,000 foreigners, among them Australians. The SDF also controls large camps for displaced persons, in which the family members of ISIS fighters are also detained. The camps are an attractive target for jailbreaks—a tactic ISIS is already encouraging. While ISIS currently lacks the resources for jailbreaks, freeing detainees will continue to be a priority focus for the organisation for pragmatic reasons relating to membership replenishment, but also because of the large-scale detention of family members. Without support the SDF lacks ‘the resources, capacity and support to detain ISIS fighters and their families indefinitely’, nor is this an adequate outcome. International efforts to ensure ISIS does not resurge in either Syria or Iraq must involve addressing the issue of ISIS detainee management and devising a longer term solution.


Back to Parliamentary Library Briefing Book

For copyright reasons some linked items are only available to members of Parliament.

© Commonwealth of Australia

Creative Commons

With the exception of the Commonwealth Coat of Arms, and to the extent that copyright subsists in a third party, this publication, its logo and front page design are licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Australia licence.