Modern violence in the Middle East is often attributed to tensions between Sunni and Shiite Muslims, an assumption bolstered by renewed fury between Saudi Arabia and Iran in recent days and fueled by rhetoric from political leaders and prominent analysts. But new data indicates bloodshed in Iraq, a central battleground for the Western war against Islamic terrorism, is caused by something altogether different.

The main driver of the violence in Iraq that contributed to the rise of the Islamic State group is the continued grievances -- perceived or otherwise -- toward the central government, according to a new study from Oregon-based aid agency Mercy Corps International. Anger and distrust toward opposing ethnic groups in Iraq could indeed contribute to future instability, but is in fact a relatively new development.

“Sectarian tension is undoubtedly worrying, and can be exploited by political actors,” Beza Tesfaye, Mercy Corps’ conflict and governance research manager, said in a statement. “But our research suggests that support for violent groups can be countered if we improve the quality of governance in Iraq, in particular its responsiveness to the needs of groups who feel marginalized.”

More than half of all Shiites and more than 80 percent of Sunnis believe the government at least sometimes treats people from their own religious group unfairly, the study finds. Most Sunnis do not support the Islamic State group, also known as ISIS, ISIL or Daesh, but many also declined to fight it in support of the central government.

All respondents believed government function worsened between 2014 and 2015 in its ability to provide general services, health care, education and electricity. Sixty percent in 2014 believed corruption worsened, which rose to more than 7o percent in 2015. Citizens’ belief that they could influence government also dropped from 2014 to 2015.

Iraq, and particularly Baghdad was not divided along strict ethnic lines before the U.S. invasion in 2003. Divisiveness increased under the Iraq Coalition Provisional Authority which, for example, mandated citizens must declare their sect on all state documents to ensure a proportionate quota of the Iraqi governing council.

Western leaders and analysts now blame government dysfunction in Iraq following the U.S. withdrawal in 2011 for the rise of the sectarian tensions that allowed the Islamic State group to sweep across the border with Syria in the summer of 2014 in its initial march on Baghdad. Former Iraqi Prime Minister Nouri al-Maliki had largely ousted Sunni Muslims and Kurds from his government, favoring his fellow Shiites and prompting complicity among other Iraqis toward the terrorist organization, which still controls massive swaths of Sunni territory.

The U.S. supported Maliki’s ouster in September 2014 and the election of current Prime Minister Haider al-Abadi, also a Shiite, who has made some attempts at greater inclusiveness toward Kurds and Sunnis. American officials continue to worry, however, that he’s not doing enough to unify the country against the extremist threat.

“Now is the time where the proof is in the pudding,” State Department spokesman Mark Toner said in late December, when asked why Iraq’s Sunnis should trust their government. “The Iraqi government [and] the Iraqi armed forces need to show that they’re actually committed to that process.”

The Iraqi government should spend more time formalizing relationships with major players in civil society, Mercy Corps recommends. The government’s input would help these leaders feel they are more directly involved in the future of Iraq, and perhaps most critically engage Iraq’s young people who are often marginalized and have been a central target of the Islamic State group’s recruitment efforts.

These kinds of stronger relationships could also encourage donors to commit greater multi-year investments in the civil society sector -- a critical source of stability currently on the decline. In 2011, the U.S. government spent roughly $80 billion per year for its troop presence of roughly 10,000 soldiers, according to the study. Now it plans to invest less than $73 million.

The government should also strengthen its post-conflict reconciliation efforts among internal groups, the study suggests, and focus on using local feedback to inform decisions and policies nationwide.

“This does not mean replicating the failures of past ‘hearts and minds’ campaigns meant to win legitimacy for the state through top-down, costly stabilization and reconstruction projects,” according to the study. “Rather, effective development can happen even as the conflict continues in Iraq, if approaches are coupled with efforts to enable Iraqi citizens to make their government deliver for them through programs that promote citizen engagement, enhance government-citizen dialogues, and mobilize civic-minded youth to be leaders.”