Peter Galbraith reviews the Iranian question:
Iran's role in Iraq is pervasive, but also subtle. When Iraq drafted its permanent constitution in 2005, the American ambassador energetically engaged in all parts of the process. But behind the scenes, the Iranian ambassador intervened to block provisions that Tehran did not like. As it happened, both the Americans and the Iranians wanted to strengthen Iraq's central government. While the Bush administration clung to the mirage of a single Iraqi people, Tehran worked to give its proxies, the pro-Iranian Iraqis it supported -- by then established as the government of Iraq -- as much power as possible. (Thanks to Kurdish obstinacy, neither the U.S. nor Iran succeeded in its goal, but even now both the US and Iran want to see the central government strengthened.)
The United States cannot now undo President Bush's strategic gift to Iran. But importantly, the most pro-Iranian Shiite political party is the one least hostile to the United States. In the battle now underway between the SIIC and Moqtada al-Sadr for control of southern Iraq and of the central government in Baghdad, the United States and Iran are on the same side. The U.S. has good reason to worry about Iran's activities in Iraq. But contrary to the Bush administration's allegations -- supported by both General David Petraeus and Ambassador Ryan Crocker in their recent congressional testimony -- Iran does not oppose Iraq's new political order. In fact, Iran is the major beneficiary of the American-induced changes in Iraq since 2003.