Military Tactics

A significant amount of ISIS’ substantial income—with a budget of $2 billion, it was considered the richest terrorist organisation the world had ever seen—was channelled to the Diwan al-Jund, ISIS’ war ministry.[1] For most of the period covered in this report, the ministry was headed by Abu Muhannad al-Suwaydawi, who succeeded Abu Abdulrahman al-Bilawi (killed in 2014) and maintained his role until his own death in 2019. Both had been former officers in the Iraqi army. Data recovered from Bilawi’s safe house revealed that around 2014, ISIS maintained around a thousand ‘medium and top-level field commanders, who all have technical, military, and security experience.[2] Among commanders, military professionalism was emphasised, and extreme discipline was enforced among its foot soldiers, who had no say over the rigid rules imposed on them.[3]

Until 2014, these commanders had been loosely connected and ISIS operated a decentralised system of military command and control, allowing local commanders a high degree of autonomy to conduct semi-conventional, highly mobile warfare. At times, ISIS would deploy terrorist attacks such as mass-casualty car bombings in civilian areas; at other times, it would use guerrilla tactics such as small-scale attacks, subversion, infiltration, and targeted assassinations with forces that were able to disperse quickly after the operations to avoid opponents’ overwhelming firepower capabilities. While small but extremely brutal attacks would weaken defences and undermine the morale of ISIS’ opponents, they were combined with highly mobile, large-scale attacks conducted with concentrated forces operating along multiple axes to overwhelm the capacity their opponents’ capacity to defend. [4]

ISIS’ high-mobility attacks were deployed effectively in Mosul and Deir Ezzor, for example, and facilitated the group’s rapid military gains in Iraq and Syria in the late spring and summer of 2014. They were made possible by the significant military assets seized from the armed forces of Iraq and, to a lesser extent, Syrian government forces and the armed opposition. The group also benefitted from arms trafficking, primarily through Turkey.[5] In late 2014, the UN Security Council Monitoring Team reported that the weaponry in ISIS‘ arsenal included:

Light weapons, assault rifles, machine guns, heavy weapons, including possible man-portable air defence systems (MANPADS) (SA 7), field and anti-aircraft guns, missiles, rockets, rocket launchers, artillery, aircraft, tanks (including T 55s and T 72s) and vehicles, including high-mobility multipurpose military vehicles.[6]

The origins of its arsenal were diverse. A three-year investigationshowed that around 90% of weapons and ammunition deployed by ISIS forces originated in China, Russia, and Eastern European countries.[7] The report also showed that ‘supplies of material into the Syrian conflict from foreign parties—notably the United States and Saudi Arabia—have indirectly allowed [ISIS] to obtain substantial quantities of anti-armour ammunition’ such as advanced anti-tank guided weapons.[8]

Following the declaration of its statelet, ISIS had competing military priorities. On the one hand, it needed more conventional armed forces to defend the territories under its control; on the other hand, conventional weapons and materiel such as heavy artillery and tanks would be more vulnerable than mobile forces to the mounting aerial attacks that had already commenced by mid-2014. In response to this challenge, ISIS set about restructuring its military apparatus into three distinct armies, to formalise the management of its armies that were fighting on different fronts.[9] ISIS’ primary conventional force was the “Caliphate Army,” operating with at least twelve divisions on different fronts across Syria and Iraq that were estimated to have several hundred to several thousand soldiers at ISIS’ peak.[10] This was supplemented by the “Dabiq Army,” made up of a loose collection of battalions of foreign fighters who served as highly mobile shock troops defending against immediate threats; and the “Al-Usra Army,” a small and specialised commando force tasked with defending Mosul.[11] Governors of ISIS-administered provinces could also draw on their personal “Army of the Wilayat” special forces.[12] ISIS’ war ministry supported the coordination of its different armies as well as logistics and administration and the procurement and development of arms and ammunition and ensured the regulation of activities according to Shari’a.[13]

ISIS’ “delegated” central committee ‘closely oversaw the organisation’s finances and had authority over the military disbursements, including battlefield bonuses for military achievements and for procurement of arms and supplies.’[14] Estimates for payments to ISIS soldiers differed, but were generally thought to be between $50 per month for unskilled volunteers and up to $1,500 per month for skilled fighters.[15] There were additional stipends for fighters with families.[16] By early 2016, however, ISIS’ finances were gradually depleted due to territorial losses and resulting declines in oil revenues. The group was forced to cut fighters’ salaries in half.[17]

Over time, the contradictions in ISIS’ model of governance and control contributed to its downfall. While ISIS had been successful in conquering territory and attracting foreign fighters to its cause, its methods left it without international allies at the same time that it faced multiple, simultaneous military campaigns that were able to deploy substantial air power in support of ground offensives. Lacking aerial capabilities itself, and without the capacity to defend against aerial attacks, ISIS’ need to control and govern territory made it increasingly vulnerable. In addition, rather than working with other Islamist or jihadist factions in Syria to make common cause against Syrian government forces, ISIS had actively fought against other groups. Although it had benefitted from a groundswell of fighters early on, it was unable to obtain the sustained support of local populations due to its rigid implementation of Salafism, which had been more uncompromising than that of any al-Qaida branch—including Jabhat al-Nusra.

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