After two years of holding territory in Iraq and Syria, the Islamic State’s ability to produce its own weapons has become so sophisticated that its production lines almost mirror those of national militaries, according to a new report by a weapons research group.

The report, authored by the United Kingdom-based Conflict Armament Research (CAR), focuses primarily on weapons production in and around the Iraqi city of Mosul. A team of researchers from the group visited the eastern reaches of the city early last month as Iraqi forces attempted to push toward its center. Iraq’s second-largest city, Mosul has been held by Islamic State forces since June 2014, and the group has fought doggedly to hold it.

CAR visited six weapons production facilities on the outskirts of Mosul for its report, documenting a range of munitions, production methods and raw material used to power the Islamic State’s war machine. In total, CAR has spent roughly 30 months assessing the Islamic State’s weapons and munitions along various fronts in Iraq and Syria.

“While previous CAR reports used the term ‘improvised weapon production,’ the phrase does not reflect the scale and sophistication of manufacturing encountered by CAR in Mosul,” the report said. “The degree of organization, quality control, and inventory management, indicates a complex, centrally controlled industrial production system.”

The research group, for instance, found mortar rounds in eastern Mosul that had been manufactured by the Islamic State in October — after Iraqi forces had begun their assault on the city. The findings led CAR to conclude that “the total number of rockets and mortars produced [by the Islamic State] must run into the tens of thousands.”

To standardize its production, the Islamic State has bought large quantities of chemicals “almost exclusively” from the Turkish domestic market, CAR said.

“These findings indicate the mass diversion of chemical precursors and a robust supply chain extending from Turkey, through Syria, to Mosul,” the report says.

The group also had its “Central Organization for Standardization and Quality Control” (COSQC) distribute blueprints to its various production facilities to ensure uniformity among parts and and final products. Through its research, CAR has found that Islamic State-built weaponry recovered from the battlefield “conforms to these standards—usually to the tenth of a millimeter.”

The Islamic State has also gone to great lengths to package and label its products in a semi-professional manner, the report says.

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