The Mahdi Army (Jaysh Al-Mahdi) militia, associated with Shi’ite cleric Muqtada Al-Sadr, became a formidable component of Shi’ite resistance to US troops and Shi’ites who supported them. The militia boasts a significant fighting force with the ability to quickly mobilize its forces. Its stronghold is located in Baghdad’s working-class suburb of Sadr City, though it also has a significant support-base in other poverty-stricken areas in the nation’s south. The militia takes its directives from Sadr, and has been responsible for a large number of US and coalition forces casualties since 2003; It engaged in intense fighting against joint US-Iraqi forces in the city of Najaf in 2004, and is suspected of having killed tens of thousands of Iraqis during heightened sectarian violence in 2006-2007. In the months prior to the US troop withdrawal from Iraq in December 2011, Sadr called off all attacks by the Mahdi Army so that, in his words, the US would have no pretext for remaining in Iraq past its deadline. He has however threatened to reinstate attacks in the case that troops do not fully withdraw by their set deadline.