In its campaign across northern Syria and Iraq, the jihadist group Islamic State has been using ammunition from the United States and other countries that have been supporting the regional security forces fighting the group, according to new field data gathered by a private arms-tracking organization.
The data, part of a larger sample of captured arms and cartridges in Syria and Iraq, carries an implicit warning for policy makers and advocates of intervention.
It suggests that ammunition transferred into Syria and Iraq to help stabilize governments has instead passed from the governments to the jihadists, helping to fuel the Islamic State’s rise and persistent combat power. Rifle cartridges from the United States, the sample shows, have played a significant role.
“The lesson learned here is that the defense and security forces that have been supplied ammunition by external nations really don’t have the capacity to maintain custody of that ammunition,” said James Bevan, director of Conflict Armament Research, the organization that is gathering and analyzing weapons used by the Islamic State.
Providing weapons to the regional proxies, Mr. Bevan added, is “a massive risk that is heightened by poorly motivated security forces that are facing great challenges.”
The Islamic State fighters have proved adept at arming themselves as they have expanded their territory. Analysts and rival rebels say the group has gathered weapons from other antigovernment groups in Syria that have joined its ranks, from purchases from Syrian rebels who receive weapons from foreign donors, from battlefield captures and from deals with corrupt members of the security forces in Syria and Iraq.
One Syrian rebel commander said the group, which is also called ISIS or ISIL, has often picked where and when to fight by measuring the potential spoils that might be gained in a local victory.
“When battling against the Syrian Army, ISIS chooses to fight in a specific battle on a specific front only when the investment is appealing: there will be warehouses to capture,” said Fouad al-Ghuraibi, commander of the Kafr Owaid’s Martyrs Brigade, in northern Syria.
After the jihadists seized a Syrian air base near Hama last year, Mr. Ghuraibi noted, they needed a fleet of heavy trucks to move their haul of captured weapons and ammunition.
He also said that a portion of the Islamic State’s ammunition had come from black-market deals with the group’s enemies, including the Syrian army, but he added that “the numbers in these deals couldn’t be high, as the officers on the regime side have had to keep it low to keep it hidden.”
Conflict Armament Research’s field survey is part of a continuing project funded by the European Union to identify the militant group’s weapons and weapon sources, and display them transparently on a global online mapping system known as iTrace. It appears to confirm and add layers of detail to what has been reported anecdotally.
Its samples included 1,730 cartridges that had been manufactured as far back as 1945 and as recently as this year. Most of the ammunition was for rifles and machine guns, though a small fraction was for pistols, too.
The ammunition was captured last summer by Kurdish fighters or collected by the organization’s investigators at recently abandoned Islamic State fighting positions. Each cartridge’s manufacturing provenance was then established by documenting its markings, known as headstamps.
Once the tallying was done, the investigators had identified 21 nations as sources of cartridges that were once possessed by Islamic State fighters, showing that these militants, like many rebel or insurgent groups, have diverse sources of supply.
A deeper look pointed to what would seem to be widespread leakage from local security forces.
More than 80 percent of the ammunition was manufactured in China, the former Soviet Union, the United States, post-Soviet Russia or Serbia. The organization’s analysis suggests that much of this ammunition was held by security forces in the region, and then commandeered by militants.
Mr. Bevan said that the aged Soviet ammunition appeared to match the contents of the storehouses of the Syrian military, which has long received equipment from the Kremlin.
Another sizable fraction of the cartridges matched ammunition that the United States supplied to Iraq’s military and police units for nearly a decade during the occupation after the American-led invasion in 2003.
“We have a lot of ammunition that comes from Iraqi security forces, which was captured on the battlefield, and a lot of ammunition that previously came from Syrian defense forces, which would be captured on the battlefield as well,” Mr. Bevan said.
Among Conflict Armament Research’s findings were that 323 of the cartridges — nearly 19 percent — were from the United States. These were typically 5.56-millimeter cartridges manufactured from 2005 to 2007 at the Lake City Army Ammunition Plant in Missouri.
The ammunition is the standard cartridge for American M-4 and M-16 rifles, which, along with these classes of rifles, was widely distributed by the United States to Iraqi security forces during the latter years of the occupation.
The sample also included 147 cartridges bearing the distinctive WOLF stamp used by Sporting Supplies International, an American company that sells Russian-manufactured ammunition under its own brand.
The company has provided bulk military ammunition to the United States government for distribution to security forces under its training, raising the possibility that an additional 8.5 percent of the ammunition documented in the Islamic State‘s possession was sent into the region by the United States.
Conflict Armament Research’s investigators also found a small sample of cartridges from Iran in the Islamic State’s possession, including ammunition manufactured as recently as 2013.
Iran has been a sponsor of Iraq’s beleaguered Shiite-led government. Ammunition from Iran, the organization noted, if deliberately transferred to Iraq, would be a violation of United Nations Security Council Resolution 1737, which in 2006 prohibited Iran from exporting arms.
On one matter, Mr. Bevan said, the data pointed to a familiar puzzle: the large proportion of Chinese ammunition — 445 cartridges or nearly 26 percent of the total.
This was not a surprise, Mr. Bevan noted, as “China is a massive supplier” of military-grade ammunition around the world, and the presence of its ammunition is a common feature in modern conflicts.
The Chinese ammunition used by the Islamic State fighters, he said, could have originally been provided to Syrian forces, to Iraqi forces or to any number of other countries that then retransferred Chinese-made cartridges to the region.