This research paper examines the extent to which both the United States (US) intervention in 2003 and sectarian conflict in Iraq and the region contributed to the rise and consolidation of the Islamic State (IS). It is argued that the US intervention contributed to the rise of IS by creating a strategic cause for mobilization of insurgency while insufficient counterinsurgency resources and doctrine, and the lack of a post-war plan enabled the insurgency to consolidate. Although the US adapted its strategy and deployed additional resources as part of the “surge,” which succeeded in weakening of the insurgents significantly, the premature withdrawal of US troops allowed for a revival of the insurgency which eventually evolved into IS. The sectarian conflict in Iraq and the region further contributed to the rise and consolidation of IS by helping in prolif-eration of the group’s underlying ideology, increasing funding opportunities for the insurgents and driving the Sunni communities to support the Islamic State