A pretty good article discussing the the issue of Iranian complicity in the Iraqi insurgency:
"The Long War Journal has spoken to several mid-level and senior US military and intelligence officers, all of whom have declined to go on the record due to the sensitive nature of the Iranian issue. Based on these conversations as well as other information, The Long War Journal has learned the nature of the Qods Force operations in Iraq and how they move resources into the country."
http://www.longwarjournal.org/archiv...azan_corps.php