During his April 2014 visit to the United States, Prime Minister Haydar al-Abbadi did not dispute assertions that the Iraqi military is about 80% Shiite Muslim—possibly explaining why some Iraqi Sunnis say they considered the ISF an "occupation force" or an "Iranian force" and might not have cooperated with it against the Islamic State's offensives. Al Qaeda in Iraq/Islamic State of Iraq and the Levant (ISIL)/Islamic State

Iraq's one-time Al Qaeda affiliate constitutes the most violent component of the Sunni rebellion that has become a major threat to Iraqi stability and a significant terrorism threat to Western countries including the United States. The Islamic State's subsequent activities, and the U.S.-led response, are analyzed in significant detail in CRS Report R43612, The Islamic State and U.S. Policy , by [author name scrubbed] and [author name scrubbed], and CRS Report R44276, The Islamic State—Frequently Asked Questions: Threats, Global Implications, and U.S. Policy Responses , coordinated by [author name scrubbed] and [author name scrubbed]. The Iraqi government promised all of the Sons of Iraq integration into the Iraqi Security Forces (ISF) or government jobs but, by the time of the U.S. withdrawal in 2011, only about two-thirds of the Sons had received these benefits. These leaders generally oppose the involvement of Shiite militiamen in Iraqi efforts to recapture Sunni-inhabited territory from the Islamic State, and instead are trying to recruit Sunni tribal fighters to spearhead government offensives against Islamic State positions. Shiite Militias and their Relations with Political Leaders

The 2006-2008 period of sectarian conflict was fueled in part by Shiite militias, such as those formed by Moqtada Al Sadr. The key militia commanders are pressing Abbadi to increase official government funding for the militias as well as to form a separate ministry to oversee and service the functioning of the PMFs. The issue of the Barzani presidency of the KRG has caused rifts within the KRG structure. However, the Kirkuk dispute has been put aside, at least temporarily, by the Kurds' seizure of Kirkuk in 2014. KRG Oil Exports

The KRG and Baghdad have been at odds over the Kurds' insistence on being able to export oil that is discovered and extracted in the KRG region. President Obama praised Abbadi in the course of their bilateral meeting at the White House on April 14, 2015, saying 
And in a significant change from some past practices, I think both Sunni leaders and Kurdish leaders feel that they are heard in the halls of power, that they are participating in governance in Baghdad ... Prime Minister Abbadi has kept true to his commitments to reach out to them and to respond to their concerns and to make sure that power is not solely concentrated within Baghdad.... Many experts assess that Abbadi remains dependent politically and militarily on the Shiite militias, and the commanders of the Iran-backed Shiite militias have become politically influential and assertive to the point where some experts assess them as able and willing to undermine Abbadi's authority. Popular Unrest Compels Reform Measures

Since mid-2015, the economic strains of confronting the Islamic State challenge manifested as popular unrest in some government-controlled areas. That proposed reform, too, has been largely stymied by entrenched resistance. U.S. Policy Response to the Islamic State51

The gains by the Islamic State in Iraq in mid-2014 posed a threat to the territorial and political integrity of Iraq, and caused the Obama Administration to resume an active military role in Iraq. The United States has deployed over 3,500 U.S. military personnel to train and advise the ISF, peshmerga forces, and Sunni tribal fighters. Regional Relationships

Iraq's neighbors have significant interest in Iraq's stability and in defeating the Islamic State, but Sunni-run governments in the region have been hesitant to work closely with the Shiite-dominated government in Baghdad. By many accounts, Iran cooperated with U.S. efforts to achieve a replacement for Maliki as Prime Minister. Turkey's positive relations with the KRG have complicated relations between Turkey and the Iraqi government. The GCC states have joined the U.S.-led coalition against the Islamic State, but have to date limited their airstrikes to Syria, not Iraq, apparently not wanting to directly materially support the Shiite-dominated government in Baghdad.
Iraq's sectarian and ethnic divisions—muted toward the end of the 2003-2011 U.S. military intervention in Iraq—are fueling a major challenge to Iraq's stability and to U.S. policy in Iraq and the broader Middle East region. The resentment of Iraq's Sunni Arabs toward the Shiite-dominated central government facilitated the capture in 2014 of nearly one-third of Iraqi territory by the Sunni Islamist extremist group called the Islamic State (IS, also known as ISIL, ISIS, or the Arabic acronym Da'esh). Iraq's Kurds are separately embroiled in political, territorial, and economic disputes with Baghdad, but those differences have been at least temporarily subordinated to the common struggle against the Islamic State.
U.S. officials assert that the Iraqi government must work to gain the loyalty of more of Iraq's Sunnis—and to resolve differences with the Kurdistan Regional Government (KRG)—if an eventual defeat of the Islamic State is to result in long-term stability. Prospects for greater inter-communal unity appeared to increase in 2014 with the replacement of former Prime Minister Nuri al-Maliki with the current Prime Minister, Haydar al-Abbadi. Although both men are from the Shiite Islamist Da'wa Party, Abbadi has taken some steps to try to compromise with Sunnis and with the KRG. However, a significant point of contention with the KRG remains the KRG's marketing of crude oil exports separately from Baghdad.
Achieving political consensus has been hindered in part by divisions within the major communities. Iraq's Sunnis remain divided between those who accept Islamic State rule and those who actively work to help the government defeat it. Within the majority Shiite community, Abbadi continues to struggle politically against the growing influence of Shiite militia commanders who operate independently of the official military chain of command, have close ties to Iranian leaders, and question the Abbadi government's alliance with the United States. The government has needed to rely on the militias in some battles against the Islamic State. Some of the Shiite militia leaders seek to combat the Islamic State without the participation of Sunni fighters, who many experts assert are key to completely defeating Islamic State forces. Divisions within the KRG have been widened by a dispute over the position of KRG President Masoud Barzani, whose term has expired but who his supporters insist should stay on in the interests of stability.
More broadly, the economic strains of fighting the Islamic State have caused economic austerity and a deterioration of services that has produced some popular unrest even in areas not directly affected by combat. Protests in Baghdad in the summer of 2014 prompted Abbadi to push for significant restructuring of the Iraqi government, and to counter corruption and excessive government spending. These efforts were supported by Iraq's highest Shiite leadership based in Najaf, but have been blunted by Iraqi politicians whose positions are threatened by reform and by many citizens who do not want their salaries cut. Factions supporting reform, including Shiites loyal to cleric Moqtada Al Sadr, have mobilized to pressure Abbadi to push forward despite the entrenched resistance.
As part of an overarching effort to defeat the Islamic State, the United States is helping the Iraqi government try to recapture territories in Iraq that have fallen under Islamic State control. The United States is conducting airstrikes against the group and has deployed over 3,500 U.S. military personnel to advise and training the Iraqi Security Forces (ISF), the Kurdish peshmerga militia, and Sunni tribal fighters. For detail on the U.S.-led efforts to defeat the Islamic State forces in Iraq, see CRS Report R43612, The Islamic State and U.S. Policy, by [author name scrubbed] and [author name scrubbed]