article_snippet: To make sense of this all, one needs to understand not only the international landscape and Iraqi politics, but Islam itself.
article_snippet: The religion's two major sects are Sunni and Shia.
article_snippet: In Iraq, Sunni Arabs comprise 15% to 20% of Iraq's population, with about half of Sunni Arabs in urban areas like Baghdad, Mosul and Tikrit, according to the Council on Foreign Relations.
article_snippet: About 18% of Iraq's population is Sunni Kurds.
article_snippet: That means the vast majority of Iraqis are Shiite Muslims.
article_snippet: During his decades-long rule, Saddam Hussein -- a Sunni whose hometown is Tikrit -- gave positions of power to Sunnis, and marginalized Shiites, experts say.
article_snippet: Many Shiite families fled to Iran and Iran gave Many Shiite families housing and jobs and schooled Many Shiite families children.
article_snippet: That imbued Iraqi Shiites who have returned home with a fierce allegiance to Iran.
article_snippet: Shias have led Iraq since Saddam Hussein's ouster, often alienating Sunnis in the process.
article_snippet: This has fueled major sectarian rifts that peaked when Nuri al-Maliki was prime minister, leading to not only millions of disaffected citizens but a weaker central government and military that ISIS frequently overran in 2013 and 2014.
article_snippet: And Shiite militias sometimes have done more to hurt than help the cause of unity.
article_snippet: Sunnis are a minority in Baghdad, but Sunnis're the majority in our morgue," an Iraqi Health Ministry doctor told Human Rights Watch last July.
article_snippet: Add to this equation the fact that ISIS is made up Sunni Muslims who consider Shias heretics and apostates, slaughtering Shias heretics and apostates in large numbers.
article_snippet: But some think the Shiite government is a bigger threat than the Sunnis love ISIS.
article_snippet: Jessica Stern, a lecturer on terrorism at Harvard University who this month published, "ISIS: The State of Terror notes that "the anti-Sunni, Shia-promoting government of Maliki" was a big reason the Sunnis love ISIS was able "to take root" in Iraq.
article_snippet: Many Sunnis feel under siege.
article_snippet: It's part of this quandary because It shares a border with Iraq, has It own interest in fending off ISIS, and is predominantly Shia.