Since the United States' military invasion and occupation of Iraq in 2003, Iran has played a crucial role in defining the future of the Iraqi state through its involvement in the internal political process. Part of Iran's strategy in Iraq has been to empower Shia political parties, which has involved the mobilisation of Shia militias in Iraq. These militias are now playing an essential role in ejecting the Islamic State, also known as ISIS or ISIL, from Iraq. There remain stiff challenges associated with the militias' post-ISIS integration into the regular Iraqi security forces and the potential for other more destabilising Iranian missions.
Iran–Iraq relations after 2003
After the US invasion of Iraq in 2003, Iraq became a focus of confrontation between Tehran and Washington. The US intervention in a Shia-majority country bordering Iran directly challenged Tehran's foreign policy, which is based substantially on anti-Americanism and anti-Zionism. To Iran the intervention also posed risks of US military encirclement. Yet although Tehran officially opposed the intervention, its response was pragmatic: it used the US invasion to consolidate a regional position that had been strengthened by the United States' removal of Saddam Hussein's minority Sunni regime, a major regional rival and a source of strategic vulnerability since the 1980–88 Iran–Iraq War. Tehran became increasingly indispensable to Iraq's post-Saddam Shia-dominated government. Tehran now enjoys a very strong voice in Iraqi politics in general, and in the building of a new Iraqi state in particular.
The state-building task, of course, remains fraught and formidable. The George W. Bush administration's Iraqi democratisation effort failed either to establish robust democracy in Iraq or to spread democracy through the region. Instead, Middle Eastern populations tended to see US occupation as heavy-handed and quasi-imperialistic, and anti-Americanism rose steeply in the region. Iraq has faced 14 years of insecurity, and the anarchical situation in many of its provinces has reinforced Iran's dominant view that democracy there means disorder. Bolstering this view was the spillover of insecurity and instability from Iraq to bordering Iranian provinces. At the same time, the United States' hobbling military and diplomatic immersion in Iraq opened new opportunities for Iran to sidestep sanctions by forging partnerships with non-Western powers, such as Russia and China, in addition to Iraq.