Understanding the Sunni involvement is essential to understand the red herring on weapons from Iran.
Kenneth Katzman , a Middle East researcher with Congressional Research Service, the research arm of Congress, said that Shi'ite militias were believed to be responsible for less than 10 percent of the total American deaths. He said most of the weapons Iran had been supplying the Shi'ite militias were believed to be for use against Sunnis. Shi'ite militias may be attacking US forces in retaliation for arrests of militia leaders, he said, but their attacks pale in comparison to the deaths inflicted by Sunni insurgents who are not believed to get assistance from Iran, he said.
"The Shi'ite militias are not the key threat to US forces in Iraq, so the overall question is why is the US military making a huge issue of this?"