ISIL has produced weapons on a scale and sophistication that matches national armies, standardising production across its self-styled caliphate, according to an arms monitoring group.
The UK-based Conflict Armament Research (CAR) said the Islamic State of Iraq and the Levant (ISIL) had a "robust supply chain" of raw materials from Turkey, and the technical precision of its work meant it could not be described as "improvised" weapons production.
"Although production facilities employ a range of non-standard materials and chemical explosive precursors, the degree of organisation, quality control, and inventory management indicates a complex, centrally controlled industrial production system," it said in a report on Wednesday, after visits last month to six facilities once operated by ISIL in eastern Mosul.
"It's consistent and organised," a technical adviser to the CAR team that visited Mosul told Al Jazeera. "It's kind of unprecedented as far as the scope of what they are creating goes, and the ability to store it and move it, and produce this variety in different sizes."
'Major acquisition network'
Iraq's military launched a sweeping operation on October 17 to retake the northern city, the armed group's last major stronghold in the country, more than two years after government forces dropped their weapons and fled in the face of a lightning-fast ISIL advance.
Elite troops have retaken a quarter of the city in a gruelling US-backed campaign, but their advance has been slow. Soldiers are constrained by street-by-street fighting and a built-up urban environment.
CAR, which identifies and tracks weapons and ammunitions in conflicts, said the facilities it visited were part of a system that produced weapons according to precise guidelines issued by a central authority.
Production included a monitoring system with regular, detailed reports on production rates and quality that helped to ensure standardisation, usually to the tenth of a millimetre, across the group's once sprawling territory in Iraq and neighbouring Syria.
CAR investigators estimated that ISIL, also known as ISIS, had produced tens of thousands of rockets and mortar rounds in the months leading to the Mosul offensive.
Standardisation required consistency in the supply of source materials, the report said, achieved through a major acquisition network in neighbouring Turkey and a supply chain extending from that country, through Syria, to Mosul.
In addition to the technical advantages of standardisation, CAR said ISIL sought to mirror the functions of a national military in an effort to "legitimise the group's capacity and coherence" in the eyes of its fighters.
The monitor also said documents it had seen in Mosul suggested ISIL had provided its fighters with sophisticated instructions on making and planting improvised explosive devices as well as the operation of complex weapons systems such as anti-tank guided missiles.
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"Improvised weapons and explosives are not something new, they’ve been used in many conflicts around the world, " said Al Jazeera's Hoda Abdel-Hamid, reporting from Bashiqua near Mosul.
"The difference here is the scale of the production. In every village, town, and in the Mosul neighbourhoods that have been recaptured, you find stockpiles left behind and often also factories."
Dan Popudik, a technical adviser to the CAR team in Iraq, told Al Jazeera they had found a large quantity of mortar rounds and rockets that had been manufactured in ISIL factories.
"At first glance from a few metres away, a lot of this stuff looks like it came out of a factory in another country that we know of, but in reality, it's homemade," he said.
Source: Al Jazeera and news agencies