Iranian support for insurgency in Afghanistan

Bill Roggio at the Long War Journal has written a good deal on Iranian support for insurgent groups in Iraq, in the form of arms, funding, and training. You can find evidence of Iranian support elsewhere as well. Perhaps lesser known is evidence of Iranian support for insurgent groups in Afghanistan. But I recently came across the following passage in Gretchen Peters's informative book on How Heroin Is Bankrolling the Taliban and Al Qaeda (on pp. 159-60):

Afghan secruity officials believe HJK (drug lord Haji Juma Khan) shifted alliances again around 2005, positioning himself as the central link between the Taliban and the subsequent surge of Iranian weapons, including shaped charges used to deadly effect against NATO troops. In June 2007, U.S. defense secretary Robert Gates complained that Iranian-made weapons were increasingly falling into Taliban hands, admitting, "We do not have any information about whether the government of Iran is supporting this, or whether it's smuggling." In fact, Afghan military and intelligence officials have unearthed evidence that HJK set up a meeting between the late Mullah Dadullah and Iranian intelligence agents to organize the flow of weapons to the insurgency. "HJK is the link between Iranian intelligence and the recent rash of IED attacks," an Afghan official told me.