From the New York Times:
This picture carries a sobering reminder for anyone who believes that arming even the most accommodating militaries and rebel groups comes without grave risks. The data set shows that the Islamic State, like many irregular forces before it, has opened spigots from varied and far-ranging sources of supply, in this case on a grand scale. The group’s diversions include ammunition that Iran most likely provided to Iraqi or Syrian security forces; weapons formerly used in wars in Libya, East Africa and the Balkans; and equipment intended for the Syrian opposition fighting President Bashar al-Assad (or even for fighting the militants themselves) but that had been sold, traded or captured from unreliable rebels.
The list of the Islamic State’s inventory reads like a roll call of arms-exporting nations: cartridges from Russia and the United States; rifles from Belgium and a host of formerly Eastern bloc states; guided anti-tank missiles from MBDA, a multinational firm with offices in Western Europe and the United States. Moreover, some of the manufacturing dates on ammunition from Kobani were remarkably recent. Investigators found Sudanese, Russian, Chinese and Iranian small-arms ammunition made from 2012 to 2014 — showing that the militant organization is a long way from being logistically isolated, no matter the forces arrayed against it. (This is not to say that the Islamic State has all the weapons that it might want, or enough of certain types; its extensive use of locally produced rockets and improvised explosive devices shows that its commanders round out arsenals with workshop-grade weapons.)
As Conflict Armament Research’s catalog grows, the implications become familiar and uncomfortable. States that arm guerrillas, brittle government security forces and other proxies tend to assume they are making discrete policy decisions. But if arms migrate as freely from one conflict or fighting force to another as the data indicates they are in the Middle East, then conflicts cannot easily be viewed, in Bevan’s words, as “ostensibly distinct.” The weapons the Islamic State came to possess were in many cases originally exported with the intention of making the region more secure, and have instead been used by militants to remove parts of two countries from the map of the civilized world, setting the group on a path to becoming the largest and most gleefully violent jihadist organization of our time.