The American-Saudi-Iranian "understanding" in Iraq:
Iran's support for al-Hakim and Sadr, prior to and after the war, eventually had to reach the point of making preferences, especially at such a critical period. The upcoming provincial council elections will determine the future of Southern Iraq and the relationship of the periphery to the central authority. It is in Iran's interest for al-Hakim to wield influence in this region which borders Iran. However, if the Mahdi Army wins the elections, which is highly probable, and continues to maintain its position unchanged, Iran will lose its long-term bet on a weak and divided Iraq. Moreover, even if al-Sadr himself supported federalism, his Movement would suffer divisions as it is constituted of diverse groups, some with Arabist and others with Islamist orientations. Consequently, this explains the repeated official and American announcements that al-Sadr is not personally targeted and that all he needs to do is to lift the political cover off al-Mahdi Army and become involved in the political process.
Biden managed to win congressional approval for his plan to partition Iraq. The new Iraqi Army, in cooperation with the militia of al-Hakim and US forces, started the implementation phase in Basra. Iran, on the other hand, awaits the opportunity to reap the gains and will have no qualms over sacrificing al-Sadr and his friendship.