How the US is doing Iran's killing in Iraq

New evidence is emerging on the ground of an Iranian hand in growing violence within Iraq, but not necessarily as the US claims Tehran is involved, that is, by providing arms to Shi'ite Muslim militants.

The massacre in Najaf last month indicates that Iran could be working through the Iraqi government, local leaders in Najaf say. The killing of 263 people in Najaf by Iraqi and US forces on January 29 provoked outrage and vows of revenge among residents in and around the sacred Shi'ite city in the south.
.... most people in the area believe the US military was told by Iraqi security forces loyal to the pro-Iranian government in Baghdad that "terrorists" or the "messianic cult" were attacking Najaf. They say the misinformation was intended to mislead occupation forces into attacking the tribe.

Many Shi'ites in the southern parts of the country and in Baghdad now say they had been fooled earlier by US promises to help them, but that the Najaf massacre has dramatically changed their views. Asia Times