The majority of weapons used by ISIS come from supplies plundered from the Iraqi military and mainly consist of stock designed or manufactured in former Soviet bloc states, according to Amnesty International.
Advances made across northern Iraq last year, particularly the capture of Mosul, gave ISIS access to a huge stockpile of arms that also included modern U.S.-made weaponry.
“We have been able to see what type of weapons they have got but in terms of quantity it’s very difficult to know that,” Patrick Wilcken, an arms control researcher at Amnesty, told Anadolu Agency.
“However, what we can say is that the top one is definitely Russian and former Soviet Union weapons. So it’s Russian and Eastern European and it’s their standard equipment that they are using.”
Wilcken said the U.S-made and NATO equipment in Daesh’s hands was a result of arms transfers made to Iraq since the 2003 U.S.-led invasion.
He added that the bulk of Daesh’s arsenal was old and dated from the 1980s and 1990s.
“The 1980s was a crucial era for arms buildup and that was the time of the Iran-Iraq War, when Russia was the principal supplier of Iraq,” Wilcken said. “But I think it’s important to remember that just because the weapons are old does not mean that they were necessarily transferred in the era they were manufactured.
“And a lot of old Warsaw Pact stock has been transferred by the U.S., the U.K., other coalition members, during the occupation of Iraq and post-2003. And even more recently, supplies to Kurdish forces in post-, mid-2014 were mainly old Warsaw Pact stock.”
ISIS also buys weapons from corrupt members of the Syrian military and on the “illicit market that runs across the borders,” Wilcken added.
“There does seem to be a lot of reports of illicit traffic. And it would be surprising if there wasn’t illicit traffic given that the whole region is in conflict.”
Improvised weapons the main issue
Although ISIS fighters have an essential stock of weapons - consisting mainly of Kalashnikov assault rifles and RPG-7 grenade launchers but also including Russian armored vehicles and tanks and U.S. Humvees - Wilckin said the main issue was not its conventional armory but improvised weapons.
“It is the improvised weapons and explosives that IS are using that has caused the most casualties in Kurdish peshmerga forces and is a really serious problem,” he said, using an alternative acronym for Daesh.
In a report issued this week, Amnesty documented the group’s use of arms and ammunition.
Taking Stock: The Arming of Islamic State reported on the use of arms supplied by at least 25 different countries including Russia, China, the U.S. and EU states.
Most weapons had been looted from Iraqi army stocks. Weapons captured in Syria also form part of the arsenal.
“Much of IS’ substantial military stocks date back to the 1980s and 1990s, drawn from the vast quantities of arms and ammunition that have been supplied to Iraq by all permanent members of the Security Council and others since the 1970s,” according to the report.
This includes equipment from “irresponsible arms supplies to Iraq organized by permanent members of the Security Council and their allies” during the Iran-Iraq war and arms supplied to Iraq by the U.S.-led coalition and other states since 2003.
"From 2003 to 2007, the U.S.A. and other coalition members transferred more than 1 million infantry weapons and pistols with millions of rounds of ammunition to the Iraqi armed forces, despite the fact that the army was poorly structured, corrupt and ill-disciplined,” Amnesty reported.
“Hundreds of thousands of those weapons went missing and are still unaccounted for. During this period, illicit markets flourished, as did covert supplies from Iran, making arms and ammunition readily available to armed groups operating in Iraq.”