The inventories for more than 465,000 small weapons — including rifles, pistols, machine guns, grenade launchers, and shotguns — that the US has shipped to Afghanistan in the past decade are a complete mess, and neither US officials nor the Afghan counterparts to whom they handed them over are really sure whether these weapons can be accounted for.

It’s hardly the first time the US military has faced serious oversight issues concerning its material investments in the Afghan National Security Forces, but a report published on Monday by the Special Inspector General for Afghanistan Reconstruction (SIGAR) — a government watchdog that is monitoring US spending in the country — paints a rather dire picture: conflicting inventories with missing and duplicate information on the US side, and on the Afghan side an even worse tracking process, with “no standardized or automated system” to account for weapons.

Complicating matters, there are also tens of thousands of additional weapons believed to be lying around… somewhere.

Considering the Department of Defense has given Afghan forces some $626 million-worth of weapons and equipment, the possibility that hundreds of thousands of weapons are sitting in abandoned warehouses or being sold on the black market is hardly ideal.

But it’s not just a matter of waste. “There is a real potential for these weapons to fall into the hands of insurgents, which will pose additional risks to US personnel, the ANSF, and Afghan civilians,” the report notes.

This doesn’t necessarily mean the weapons that the US can’t properly account for are in the hands of the Taliban — or whether they’re even missing. Officials simply aren’t sure.

“Because the logistics and inventory records are so poor, we can’t determine if they’re just not accounted for correctly but they’re somewhere, or if they’re lost or stolen,” Jeffrey Brown, a senior auditor behind the report, told VICE News. “That’s how bad the inventory records on the Afghan side are.”

Brown declined to discuss specific instances of US weapons being used against US citizens or interests in Afghanistan.

“But in a very theoretical way, if you were to find a weapon you could find out whether the weapon originated in a US factory and, for example, if it was captured from an enemy or used against an American citizen,” Brown said. “If you were able to recover it, you’d be able to tell if we purchased it. The problem is the chain of custody between when it was used against, say, a US soldier and when it was produced in a factory. We can’t determine who had it and who had responsibility for it in that process, and ultimately where it left the chain of custody and who would be held responsible for that weapon being out there.”

The problem of missing weapons and ammunition is not new — it happened in Iraq and has been an issue in Afghanistan for years.

In 2009, a New York Times reporter examined weapons and rifle magazines found on the bodies of dead insurgents, and determined that more than half of the magazines held ammunition identical to cartridges provided by US officials to the Afghan forces they trained, “strongly” suggesting the possibility that “munitions procured by the Pentagon have leaked from Afghan forces for use against American troops.”

Local reports have also supported this possibility, with some documenting increasing evidence that Afghan police “are happily trading away their ammunition to the insurgents they are supposed to be shooting at.”

“Unfortunately, a proportion of the weapons and equipment assigned to our national army, police, and security agency are now in the hands of our opponents," Mohammad Ali Ahmadi, deputy governor of Ghazni province, in southeastern Afghanistan, told the Institute for War and Peace Reporting (IWPR) late last year.

In other districts, the traffic of stolen or “leaked” US weapons has started to surpass the opium trade.

“There’s a village in our area called Qala-ye Sayed Sadeq. Weapons are traded there on a regular basis,” Borhan, a resident in Nangarhar Province, near the Pakistan border, told IWPR. “The police send weapons and bullets there via arms smugglers. The Taliban come at night in their cars and buy weapons there and take them away.”

Police elsewhere said that the equipment handovers are done overnight, sometimes using a trained donkey that police load up with ammo before sending it back to the Taliban.

The problem of unaccounted equipment is worsened by the fact that thousands of weapons that were deemed to be in “excess” were never returned or disposed of, SIGAR said.

For instance, the report found that the Afghan National Security Forces have 83,184 more AK-47s than they require.

“The US agencies involved and the Afghan government know the overages are there, they’re just basically leaving it as is and making no claim to utilize them,” Brown said. “But the real danger inherent in unutilized weapons is more than in used weapons: if weapons are part of a large stock that is unutilized, unfortunately those could be sold or lost, and they are much more vulnerable to ending up on the black market or having some unintended persons using them.”

In the report, SIGAR recommended reconciling the conflicting US databases and working with the Afghans to complete a “100 percent inventory check” of small arms they received. It also suggested making future weapon supplies contingent on the ANSF getting its tracking system in order.

But counting the weapons that can be found is hardly a fix when you don’t know how many there are supposed to be — or where they’re supposed to be.

“When you check the inventory against flawed inventory records, it’s a crapshoot whether you’re actually going to identify anything or not,” Brown said.

Follow Alice Speri on Twitter: @alicesperi