A US-led coalition invaded Iraq and removed Saddam Hussein from power in 2003. The invasion unleashed sectarian violence and an insurgency against coalition troops, which included al-Qaeda-affiliated terrorist attacks. The security situation was at best tenuous when the US withdrew from Iraq in December 2011, with near-daily sectarian violence, exacerbated by the rule of former prime minister Nuri al-Maliki, who alienated Iraq’s Sunni community. The situation deteriorated with the outbreak of civil war in neighbouring Syria and the emergence of the Islamic State, also known as ISIS or ISIL. ISIS emerged from al-Qaeda in Iraq, a central group in the anti-American insurgency that had been neutralised with the assistance of Sunni militia groups known as Sahwa (Awakening). ISIS captured large swathes of territory in Iraq, including the second-largest city Mosul, in June 2014, setting up a ‘Caliphate’, while looting weapons, oil and other resources. Over the next three years, it was pushed out of Iraqi territories, with an operation to recapture Mosul, its last remaining stronghold, making significant gains.
An array of groups are involved in battles against ISIS, including a US-led coalition, which provides airstrikes and military assistance to Iraqi troops and allied militias, particularly the Kurdish Peshmerga. Furthermore, al-Hashd al-Shaabi (Popular Mobilisation Units), an umbrella of powerful militias have participated in ground operations against ISIS. The diverse militias have various allegiances – some are loyal to Iran, others to Grand Ayatollah Ali al-Sistani, and others to Maliki, who has continued to meddle in Iraqi politics. The presence of groups with different and often clashing objectives has resulted in political paralysis and undermined the potential of an inclusive post-ISIS political settlement.