"Scattered Shias, Sunni spells"

It worries me that tonight's lead story surrounding the US revelation that "a growing body of evidence" points to Iran supplying weapons to insurgents in Iraq, fails to acknowlege the obvious fact that the Shia militias that Iran is most likely to support, have proven far less deadly to the invaders than the Sunni ones. 170 coalition deaths are cited. This is really a small percentage of the total. Where are the Sunnis getting their roadside bombs from then? (Answers on a postcard)