I thought Shiites and Sunnis were not supposed to be cooperating. It's just gotta be Bush's fault.  Robin Wright in the WaPo:

An Iranian arms shipment destined for the Taliban was intercepted on Sept. 6 by the international force in Afghanistan in what appears to be an escalating flow of weaponry between the two former enemies, according to officials from countries in the NATO-led International Security Assistance Force.

The shipment included armor-piercing bombs known as explosively formed projectiles, which have been especially deadly when used as roadside bombs against foreign troops in Iraq, the sources said. The NATO-led force interdicted two smaller shipments of similar weapons coming from Iran into southern Helmand province on April 11 and May 3.

"It's not the fact that it's qualitatively different, but this was a large shipment which got people's attention," a U.S. official in Washington said.