This report examines Iran's influence in Iraq post-Saddam. This is in large part because the dominant parties in Iraq have long-standing ideological, political, and religious sectarian ties to Tehran. A key U.S. concern is that Iran, seeking to ensure the political prospects of its proteges, supports Shiite militias that are committing sectarian violence. Since December 2006, the Administration has tried to reverse Iranian influence in Iraq while also engaging Iran diplomatically on Iraq.