120mm --- Are you referring to the Sunni insurgency, or the Shia militia groups? For me it's much harder to discover why any Iraqis are actually fighting with us rather than the converse, actually. Nationalism, religious zeal, collateral damage, a cultural history in the west of Iraq predicated on tribal revenge, an honor culture, and lots and lots of unemployed, military-age males with a modicum of military training and plenty of weaponry. Is it so hard to figure out? I think if one goes back to the Peninsular War, one would find many parallels.