According to an article in the web-based Iran Press Service, there are growing tensions between the ruling mullahs in Iran and Shi’ite groups in Iraq, including the Supreme Assembly for Islamic Revolution in Iraq (SAIRI), a formerly pro-Iranian group led by Abdul-Aziz Al-Hakim and once based in Iran. In its desire to cause trouble for the US, Iran helped al-Sadr in his now failed power grab, which undoubtedly irritated other Shi’ite leaders like Al-Hakim and Sistani and threatened to harm the position of the Shi’ites as a whole with the US.
As the article makes clear, the Shi’a need the US to achieve their fundamental political goal: to ensure that the Iraqi Shi’a are never again in a powerless position to be dominated and persecuted by others. This goal explains their sometimes contradictory attitudes and actions toward the US: attacking the US "occupation" while clearly helping our forces against Al-Sadr; denouncing Coalition actions in Fallujah while panicking when the US allowed a former Saddam general (and a Sunni) to try to pacify the area; and cautiously supporting the Kurds’ desire for regional autonomy so long as it doesn’t threaten the idea of Iraq as one country governed by a democratic majority. The Shi’ites’ guiding interest makes them difficult at times and certainly not unabashedly pro-US like the Kurds, but it also gives the Coalition a real ground of negotiation and even cooperation with them in the difficult days coming with the transfer of sovereignty.