Malou Innocent. “The Iraq war: still a massive mistake.” Christian Science Monitor. April 5th, 2010: “The war also upset the regional balance of power, as it substantially strengthened Iran’s influence in Iraq and severely limited US policy options toward Tehran’s clerical regime. No amount of prewar planning or “boots on the ground” could have prevented the Islamic Republic’s political push into a neighboring country with a 60 percent Shiite majority. The removal of Saddam Hussein as the principal strategic counterweight to Iran paved the way for the expansion of Iranian influence in Iraq, and has enabled Tehran to back, with far greater impunity, its political allies in Baghdad.
Even before 9/11, Iran possessed a budding nuclear program, the region’s largest population, an expansive ballistic-missile arsenal, and significant influence over the Lebanese Shiite group Hezbollah. By adding to that list enhanced political influence in Iraq, Iran can be somewhat more assertive geopolitically in the region, further limiting US policy options.”
Francis Fukuyama. “Iraq May Be Stable, But the War Was a Mistake” Wall Street Journal. August 15th, 2008: “Indeed, Iran has emerged as the dominant regional power in the Persian Gulf once the U.S. removed its major rival from the scene and put its Shiite clients into power in Baghdad.”