Worth a read today (especially in light of this) is a Council On Foreign Relations backgrounder at the New York Times:
U.S. officials say they have found evidence that Iran has supplied weapons to Taliban rebels operating along the Afghan-Pakistani border.I've mentioned those Pakistan arms bazaars before myself - they boast they can copy even a missile down to the markings in such detail you cannot tell their copy from the original. I've also written about how the ages-old useage of the Silk Road network in the region facilitates smuggling and makes borders impossibly porous from Algiers to Islamabad. Occam's Razor suggests strongly that black-market private enterprise and a few rogue or corrupt individuals is sufficient to explain arms movements in the region without conjuring conspiracy theories involving the Iranian leadership (or, in the case of Kurdish terrorists, the Israeli leadership).
...experts disagree whether the Iranian government is directly involved. Some say the weapons could have been smuggled into Afghanistan via various third-party channels. Others suggest they are being supplied by hard-line components within the Iranian Revolutionary Guards, which has a separate agenda from the Iranian foreign ministry, which in turn has a separate agenda from Iran’s business community. “We’re talking about rogue elements,” says Col. Christopher Langton, a senior fellow at the International Institute for Strategic Studies, “maybe even cross-border organizational criminal groupings.” He adds that arms factories in Pakistan’s Northwest Frontier Province make copies of those weapons made in Iran.
The backgrounder goes on to speculate about possible Iranian motives for playing the field in their support for both Afghanistan and its enemies. And the important word is speculation - no matter how much it may make sense, if you don't have hard evidence then you don't know for sure. One of the simplest deceptions of the Bush administration's warmonger faction is that they've always been glib about the verbal sidestep from "guess that" to "assess that" to "know that". Then the US ends up invading another nation on what are still just guesses but are being passed off as "slam dunk" certainties.