<P> While the majority of Muslims in Iraq are Shia, the country has been ruled for decades by Sunni - dominated governments under the Ottoman Empire, the British - installed Hashemites, and the Ba'athists . Under the rule of Saddam Hussein, Iraq was hostile to both Iran and Saudi Arabia and acted as a counterbalancing regional power . The American - led invasion in 2003 caused a power vacuum in the region . With the antagonistic Ba'athist regime removed, Iran sought a more friendly Shia - dominated government and supported sympathetic rebel factions as part of an effort to undermine the coalition, which Iran feared would install a government hostile to its interests . </P> <P> Saudi Arabia remained more passive during the occupation of Iraq, taking caution to preserve its relations with the United States by avoiding any direct support of Sunni insurgent groups . Riyadh supported the Bush administration's commitment to stay in the country, as it limited Iran's influence . The edicts issued in May 2003 by Coalition Provisional Authority Administrator Paul Bremer to exclude members of the Ba'ath Party from the new Iraqi government and to disband the Iraqi Army undermined the occupation effort . The orders empowered various insurgent factions and weakened the new government's functional capabilities, leaving Iraq vulnerable to future instability . </P> <P> Following the United States withdrawal from Iraq in December 2011, the country drifted further into Iran's sphere of influence . The instability that resulted from the Iraqi Civil War and the rise of ISIL threatened the existence of the Iraqi regime and led to an Iranian intervention in 2014 . Iran mobilized Shia militia groups to halt and ultimately push back the advancing Sunni insurgency . </P> <P> The Iraqi government remains particularly influenced by Iran, and consults with it on most matters . As of 2018 Iran has become Iraq's top trading partner, with an annual turnover of approximately $12 billion USD compared to the $6 billion USD in trade between Iraq and Saudi Arabia . In addition to fostering economic ties, Tehran furthered its influence by aiding the Iraqi government in its fight against the push for independence in Iraqi Kurdistan . Saudi Arabia has responded by strengthening its ties to the Kurdistan Regional Government, seeing it as a barrier to the expansion of Iranian influence in the region, while also adopting a soft power approach to improve relations with the Iraqi government . </P>

What two groups represent the middle eastern conflict in iraq