Is Iran Arming U.S. Enemies in Afghanistan?

In March 2011, veteran Afghan journalist Najibullah Quraishi trekked to a remote part of north-central Afghanistan. He had been invited by a group of Afghan Arab insurgents who pledged their loyalty to Osama bin Laden.

During Quraishi's two weeks with them, they made a bold assertion: that Iran was giving them weapons, specifically rocket-propelled grenades and launchers, to use in their fight against American and NATO troops.

They weren't the first to make the claim. Since 2007, NATO and U.S. officials have repeatedly stated that international and Afghan government forces have intercepted Iranian-manufactured weapons -- from rocket propelled grenades and "upscale" roadside bombs to mines and armor-piercing bombs -- intended for the Taliban in Afghanistan. Just recently, NATO officials said coalition forces intercepted 48 Iranian-made rockets intended for Taliban fighters in Afghanistan.

Were these insurgents offering new evidence that these enemies of the U.S. are colluding to fight its forces in Afghanistan? Or was this just the latest in what has become a series of murky claims and counterclaims that are an undercurrent of the conflict?

While claims about a connection are widespread, proof is often harder to come by. Weapons experts can look to the evident design of the weapons. For instance, some technical details can match other Iranian models that were supplied by Iran to insurgents in Iraq. But an expert at London's International Institute for Strategic Studies told the Council on Foreign Relations in 2006 that flourishing arms factories in Pakistan's northwest can make copies of weapons made in Iran. Some have raised the possibility of intentional, politically-motivated fabrications. Experts can look to serial numbers, but some claim an absence of serial numbers can be even more suggestive of an intentional covert effort.

And even if experts can establish that a weapon originated in Iran, can they also be traced to the Iranian regime as U.S. officials claim? Some have claimed weapons can easily be smuggled across Iran's 581-mile border with Afghanistan through third-party channels. There have been reports that Iranian businessman sell weapons in the illicit black market. Beyond that, the Iranian regime may not be unified. Author and former State Department advisor Vali Nasr says Iran's military may have rogue elements acting without the sanction of seniors.

Iran has denied the allegations, calling the Taliban "enemies of Iran" and referencing its historically hostile relationship with the Taliban when they were in power in Afghanistan.

But analyst Peter Bergen told FRONTLINE that it could serve Iranian interests by increasing the costs of U.S. presence in Afghanistan and resulting in a more rapid U.S. withdrawal. Bordered by Afghanistan -- where 100,000 U.S. troops are on the ground -- and Iraq, Iran is uncomfortable with the idea that it could be encircled by countries with permanent U.S. bases from which to strike Iran.

"Iranians have a much more nuanced foreign policy than we assume," says Vali Nasr. He told FRONTLINE that while the Iranian-manufactured weapons found in Afghanistan are not necessarily coming from the Iranian government, if they are, they could be one method to remind the U.S. periodically of their influence in the region and "what they can do."

That certainly fits what Gen. David Petraeus told the Senate Armed Services Committee last March [PDF]. "They want to provide enough assistance to the Taliban so that they make life difficult for us and others," Peraeus testified, "but not so much that they might actually succeed."

And although it can't be independently confirmed because it is classified, U.S. officials say that they have direct human intelligence beyond simply the physical weapons to establish the link.

In the case of these particular claims made to Najibullah Quraishi, though, the evidence appears relatively clear.

FRONTLINE asked U.S. Army experts to examine pictures of some of the weapons these insurgents showed Quraishi.

Based on that examination, they told us it was "highly unlikely" that these particular weapons were manufactured in Iran. In fact, they said that the launcher was most likely Chinese-manufactured and the grenades most likely Bulgarian.