The Sunni-Shia Divide

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An ancient religious divide is helping fuel a resurgence of conflicts in the Middle East and Muslim countries. Struggles between Sunni and Shia forces have fed a Syrian civil war that threatens to transform the map of the Middle East, spurred violence that is fracturing Iraq, and widened fissures in a number of tense Gulf countries. Growing sectarian clashes have also sparked a revival of transnational jihadi networks that poses a threat beyond the region.

Islam’s schism, simmering for fourteen centuries, doesn’t explain all the political, economic, and geostrategic factors involved in these conflicts, but it has become one prism through which to understand the underlying tensions. Two countries that compete for the leadership of Islam, Sunni Saudi Arabia and Shia Iran, have used the sectarian divide to further their ambitions. How their rivalry is settled will likely shape the political balance between Sunnis and Shias and the future of the region, especially in Syria, Iraq, Lebanon, Bahrain, and Yemen.

Alongside the proxy battle is the renewed fervor of armed militants, motivated by the goals of cleansing the faith or preparing the way for the return of the messiah. Today there are tens of thousands of organized sectarian militants throughout the region capable of triggering a broader conflict. And despite the efforts of many Sunni and Shia clerics to reduce tensions through dialogue and counterviolence measures, many experts express concern that Islam’s divide will lead to escalating violence and a growing threat to international peace and security.

Sunni and Shia Muslims have lived peacefully together for centuries. In many countries it has become common for members of the two sects to intermarry and pray at the same mosques. They share faith in the Quran and the Prophet Mohammed’s sayings and perform similar prayers, although they differ in rituals and interpretation of Islamic law.

Shia identity is rooted in victimhood over the killing of Husayn, the Prophet Mohammed’s grandson, in the seventh century, and a long history of marginalization by the Sunni majority. Islam’s dominant sect, which roughly 85 percent of the world’s 1.6 billion Muslims follow, viewed Shia Islam with suspicion, and extremist Sunnis have portrayed Shias as heretics and apostates.

Mohammed unveiled a new faith to the people of Mecca in 610. Known as Islam, or submission to God, the monotheistic religion incorporated some Jewish and Christian traditions and expanded with a set of laws that governed most aspects of life, including political authority. By the time of his death in 632, Mohammed had consolidated power in Arabia. His followers subsequently built an empire that would stretch from Central Asia to Spain less than a century after his death. But a debate over succession split the community, with some arguing that leadership should be awarded to qualified individuals and others insisting that the only legitimate ruler must come through Mohammed’s bloodline.

A group of prominent early followers of Islam elected Abu Bakr, a companion of Mohammed, to be the first caliph, or leader of the Islamic community, over the objections of those who favored Ali ibn Abi Talib, Mohammed’s cousin and son-in-law. The opposing camps in the succession debate eventually evolved into Islam’s two main sects. Shias, a term that stems from shi’atu Ali, Arabic for “partisans of Ali,” believe that Ali and his descendants are part of a divine order. Sunnis, meaning followers of the sunna, or “way” in Arabic, of Mohammed, are opposed to political succession based on Mohammed’s bloodline.

Ali became caliph in 656 and ruled only five years before he was assassinated. The caliphate, which was based in the Arabian Peninsula, passed to the Umayyad dynasty in Damascus and later the Abbasids in Baghdad. Shias rejected the authority of these rulers. In 680, soldiers of the second Umayyad caliph killed Ali’s son, Husayn, and many of his companions in Karbala, located in modern-day Iraq. Karbala became a defining moral story for Shias, and Sunni caliphs worried that the Shia Imams—the descendants of Husayn who were seen as the legitimate leaders of Muslims (Sunnis use the term “imam” for the men who lead prayers in mosques)—would use this massacre to capture public imagination and topple monarchs. This fear resulted in the further persecution and marginalization of Shias.

Even as Sunnis triumphed politically in the Muslim world, Shias continued to look to the Imams—the blood descendants of Ali and Husayn—as their legitimate political and religious leaders. Even within the Shia community, however, there arose differences over the proper line of succession. Mainstream Shias believe there were twelve Imams. Zaydi Shias, found mostly in Yemen, broke off from the majority Shia community at the fifth Imam, and sustained imamate rule in parts of Yemen up to the 1960s. Ismaili Shias, centered in South Asia but with important diaspora communities throughout the world, broke off at the seventh Imam. Most Ismailis revere the Aga Khan as the living representative of their Imam. The majority of Shias, particularly those in Iran and the eastern Arab world, believe that the twelfth Imam entered a state of occultation, or hiddenness, in 939 and that he will return at the end of time. Since then, “Twelvers,” or Ithna Ashari Shias, have vested religious authority in their senior clerical leaders, called ayatollahs (Arabic for “sign of God”).  

Many Christian, Jewish, and Zoroastrian converts to Islam chose to become Shia rather than Sunni in the early centuries of the religion as a protest against the ethnic Arab empires that treated non-Arabs as second-class citizens. Their religions influenced the evolution of Shia Islam as distinct from Sunni Islam in rituals and beliefs.    

Sunnis dominated the first nine centuries of Islamic rule (excluding the Shia Fatimid dynasty) until the Safavid dynasty was established in Persia in 1501. The Safavids made Shia Islam the state religion, and over the following two centuries they fought with the Ottomans, the seat of the Sunni caliphate. As these empires faded, their battles roughly settled the political borders of modern Iran and Turkey by the seventeenth century, and their legacies resulted in the current demographic distribution of Islam’s sects. Shias comprise a majority in Iran, Iraq, Azerbaijan, and Bahrain, and a plurality in Lebanon, while Sunnis make up the majority of more than forty countries from Morocco to Indonesia.

Iran’s Islamic Revolution in 1979 gave Shia cleric Ayatollah Ruhollah Khomeini the opportunity to implement his vision for an Islamic government ruled by the “guardianship of the jurist” (velayat-e faqih), a controversial concept among Shia scholars that is opposed by Sunnis, who have historically differentiated between political leadership and religious scholarship. Shia ayatollahs have always been the guardians of the faith. Khomeini argued that clerics had to rule to properly perform their function: implementing Islam as God intended, through the mandate of the Shia Imams.

Under Khomeini, Iran began an experiment in Islamic rule. Khomeini tried to inspire further Islamic revival, preaching Muslim unity, but supported groups in Lebanon, Iraq, Afghanistan, Bahrain, and Pakistan that had specific Shia agendas. Sunni Islamists, such as the Muslim Brotherhood and Hamas, admired Khomeini’s success, but did not accept his leadership, underscoring the depth of sectarian suspicions.

Saudi Arabia has a sizable Shia minority of roughly 10 percent, and millions of adherents of a puritanical brand of Sunni Islam known as Wahhabism (an offshoot of the Sunni Hanbali school) that is antagonistic to Shia Islam. The transformation of Iran into an overtly Shia power after the Islamic revolution induced Saudi Arabia to accelerate the propagation of Wahhabism, as both countries revived a centuries-old sectarian rivalry over the true interpretation of Islam. Many of the groups responsible for sectarian violence that has occurred in the region and across the Muslim world since 1979 can be traced to Saudi and Iranian sources.

Saudi Arabia backed Iraq in the 1980–1988 war with Iran and sponsored militants in Pakistan and Afghanistan who were primarily fighting against the Soviet Union, which had invaded Afghanistan in 1979, but were also suppressing Shia movements inspired or backed by Iran.

The transformation of Iran into an agitator for Shia movements in Muslim countries seemed to confirm centuries of Sunni suspicions that Shia Arabs answer to Persia. Many experts, however, point out that Shias aren’t monolithic—for many of them, identities and interests are based on more than their confession. Iraqi Shias, for example, made up the bulk of the Iraqi army that fought Iran during the Iran-Iraq War, and Shia militant groups Amal and Hezbollah clashed at times during the Lebanese civil war. The Houthis, a Zaydi Shia militant group in Yemen, battled the government of Ali Abdullah Saleh, a Zaydi, several times between 2004 and 2010. Then, in 2014, the Houthis captured the capital Sana’a with ousted president Saleh’s support.

For their part, both mainstream and hard-line Sunnis aren’t singularly focused on oppressing Shias. They have fought against coreligionists throughout history, most recently in the successive crackdowns on the Muslim Brotherhood in Egypt, Iraq’s 1990 invasion of Kuwait, and Saudi Arabia’s battles against al-Qaeda and related Sunni militant groups. Sharing a common Sunni identity didn’t eliminate power struggles among Sunni Muslims under secular or religious governments.

But confessional identity has resurfaced wherever sectarian violence has taken root, as in Iraq after the 2003 U.S.-led invasion removed Saddam Hussein, a dictator from the Sunni minority who ruled over a Shia-majority country. The bombing of a Shia shrine in Samara in 2006 kicked off a cycle of sectarian violence that forced Iraqis to pick sides, stirring tensions that continue today.

In the Arab world, Shia groups supported by Iran have recently won important political victories. The regime of Syrian President Bashar al-Assad, which has ruled since 1970, relies on Alawis, a heterodox Shia sect that makes up about 13 percent of Syria’s population, as a pillar of its power. Alawis dominate the upper reaches of the country’s military and security services and are the backbone of the forces fighting to support the Assad regime in Syria’s civil war. Since the 2003 invasion of Iraq unseated Saddam Hussein and instituted competitive elections, the Shia majority has dominated the parliament and produced its prime ministers. Hezbollah, the Lebanese Shia militia and political movement, is the strongest party in Lebanon. The Houthis, Shia militants in Yemen tenuously linked to Iran, have toppled the country’s internationally recognized government. Iran, a majority Shia country, has seen its regional influence swell as its allies in these countries have accumulated power.

Sunni governments, especially Saudi Arabia, have increasingly worried about their own grips on power, a concern that was exacerbated during the protest movement that began in Tunisia in late 2010. The Arab Awakening, as the uprisings are known, spread to Bahrain and Syria, countries at the fault lines of Islam’s sectarian divide. In each, political power is held by a sectarian minority—Alawis in Syria and a Sunni ruling family in Bahrain—where Shias are the majority. In Yemen, Houthi rebels have expanded their territorial control, which Saudi Arabia perceives as a potential beachhead for Iran on the Arabian peninsula, along vital shipping routes in the Red Sea and in territory abutting Saudi Arabia’s own marginalized Shia minority. 

Sunnis and Shias agree on the basic tenets of Islam: declaring faith in a monotheistic God and Mohammed as his messenger, conducting daily prayers, giving money to the poor, fasting during the Muslim holy month of Ramadan, and performing the pilgrimage to Mecca.

There are divisions even over the precepts of Islam, but the main difference relates to authority, which sparked the political split in the seventh century and evolved into divergent interpretations of sharia, or Islamic law, and distinct sectarian identities.

Shias believe that God always provides a guide, first the Imams and then ayatollahs, or experienced Shia scholars who have wide interpretative authority and are sought as a source of emulation. The term “ayatollah” is associated with the clerical rulers in Tehran, but it’s primarily a title for a distinguished religious leader known as a marja, or source of emulation. Iran’s supreme leader, Ali Khamenei, was appointed by an elected body of Iranian clerics, while maraji (plural of marja) are elevated through the religious schools in Qom, Najaf, and Karbala. Shias can choose from dozens of maraji, most of whom are based in holy cities in Iraq and Iran. Many Shias emulate a marja for religious affairs and defer to Supreme Leader Ali Khamenei in Iran for political guidance. For Sunnis, authority is based on the Quran and the traditions of Mohammed. Sunni religious scholars, who are constrained by legal precedents, exert far less authority over their followers than their Shia counterparts.

Both sects have subdivisions. The divisions among Shias were discussed above. Four schools comprise Sunni jurisprudence: Hanafi, Shafii, Maliki, and Hanbali, the latter spawning the Wahhabi and Salafi movements in Saudi Arabia. Sunnism, a broad umbrella term for non-Shia Islam, is united on the importance of the Quran and practice of Mohammed but allows for differences in legal opinion.

Violence between Islam’s sects has been rare historically, with most of the deadly sectarian attacks directed by clerics or political leaders rather than erupting spontaneously. Extremist groups, many of which are fostered by states, are the chief actors in sectarian killings today.

Two of the most prominent terrorist groups, Sunni al-Qaeda and Shia Hezbollah, have not defined their movements in sectarian terms, and have favored using anti-imperialist, anti-Zionist, and anti-American frameworks to define their jihad, or struggle. They share few similarities beyond the use of violence. Hezbollah has developed a political wing that competes in elections and is part of the Lebanese government, a path not chosen by al-Qaeda, which operates a diffuse network largely in the shadows. Both groups have deployed suicide bombers, and their attacks shifted from a focus on the West and Israel to other Muslims, such as al-Qaeda’s killing of Shia civilians in Iraq and Hezbollah’s participation in the Syrian civil war.

Conflict and chaos have played a role in the reversion to basic sectarian identity. In Iraq, for instance, remnants of Hussein’s Ba’athist regime, as well as militants whose organization would eventually become the self-proclaimed Islamic State, employed Sunni rhetoric to mount a resistance to the rise of Shia power. Sunni fundamentalists, many inspired by al-Qaeda’s call to fight Americans, flocked to Iraq from Muslim-majority countries, attacking coalition forces and many Shia civilians. Abu Musab al-Zarqawi, who founded al-Qaeda’s franchise in Iraq, evoked ancient anti-Shia fatwas, or religious rulings, to spark a civil war in hopes that the Shia majority would eventually capitulate in the face of Sunni extremist violence. Iraq’s foremost Shia religious authority, Grand Ayatollah Ali al-Sistani, has been a voice for sectarian restraint in Iraq, and the country’s Shia community absorbed thousands of deaths before fighting back with their own militias. But, during the U.S. occupation of Iraq and, more recently, offensives against the Islamic State, Shia paramilitaries have been accused of possible war crimes.

Syria’s civil war, in which a quarter million people have been killed and eleven million—more than half the country’s prewar population—displaced, has amplified sectarian tensions to unprecedented levels. The war began with peaceful protests in 2011 calling for an end to the Assad regime. Decades of the Assad family's repression of Syria’s majority Sunni population and elevation of minority Alawis in government and the private sector has sown sectarian strife. The 2011 protests and brutal government crackdown uncovered sectarian tensions, which have rippled across the region.

Tens of thousands of Syrian Sunnis joined rebel groups such as Ahrar al-Sham, the Islamic Front, and al-Qaeda’s Nusra Front, which all employ anti-Shia rhetoric; similar numbers of Syrian Shias and Alawis enlisted with an Iran-backed militia known as the National Defense Force to fight for the Assad regime. Sunni fighters from Arab and Western countries initially joined the Syrian rebels before turning their guns on them in an effort to establish their envisaged caliphate. Meanwhile Hezbollah and some Shia militias from Iraq, such as Asaib Ahl al-Haq and Kata’ib Hezbollah, backed the Syrian government. Syria’s civil war has attracted more militants from more countries than were involved in the conflicts in Afghanistan, Chechnya, and Bosnia combined.

Al-Qaeda in Iraq had been decimated by Sunni Iraqis who joined the fight against extremists, the U.S.-led military surge, and the death of Zarqawi, its leader, in a 2006 U.S. airstrike, but found new purpose  exploiting the vacuum left by the receding Syrian state. It established its own transnational movement known as the Islamic State in Iraq and Syria. The group expanded its grip on Sunni provinces in Iraq and eastern regions in Syria, seizing Iraq’s second-largest city, Mosul, in June 2014. It defied orders from al-Qaeda’s top commanders to curtail its transnational ambitions and wanton violence against civilians, which led to the militant group’s expulsion from al-Qaeda in February 2014. ISIS rebranded as the Islamic State in July 2014 and declared its leader, Abu Bakr al-Baghdadi, as caliph. The group’s highly publicized killing of Western hostages triggered a campaign of air strikes by the United States and its regional allies Jordan, Qatar, Saudi Arabia, and the United Arab Emirates.

Extremist groups have come to rely on satellite television and high-speed Internet over the past two decades to spread propaganda and attract recruits. Fundamentalist Sunni clerics, many sponsored by wealthy Sunnis from Saudi Arabia and the Gulf states, have popularized anti-Shia slurs. Shia religious scholars have also taken to the airwaves, mocking and cursing the first three caliphs and Aisha, one of Mohammed’s wives.

Sectarian rhetoric dehumanizing the “other” is centuries old. But the volume is increasing. Dismissing Arab Shias as Safawis, a term that paints them as Iranian agents (from the Safavid empire) and hence traitors to the Arab cause, is increasingly common in Sunni rhetoric. Hard-line Sunni Islamists have used harsher historic terms, such as rafidha, rejecters of the faith, and majus, Zoroastrian or crypto Persian, to describe Shias as heretical. Iranian officials, Iraqi politicians, and Hassan Nasrallah, the leader of Hezbollah, routinely describe their Sunni opponents as takfiris (referring to the doctrine embraced by al-Qaeda of declaring fellow Muslims apostate) and Wahhabis (referring to the puritanical Saudi sect). This cycle of demonization has been amplified throughout the Muslim world.

For Sunni extremists, social media has revolutionized recruitment opportunities. Fundamentalists no longer have to infiltrate mainstream mosques to attract recruits surreptitiously, but can now disseminate their call to jihad and wait for potential recruits to contact them. Shia groups can count on state support from the Iranian, Iraqi, and Syrian governments to recruit militants for sectarian jihad.

Sunni-Shia tensions contribute to multiple flash points in Muslim countries that are viewed as growing threats to international peace and security. The following arouse the most concern among regional specialists:

Sectarian violence intensified in 2013 and has grown since. Extremists were “fueled by sectarian motivations” in Syria, Lebanon, and Pakistan, according to the U.S. State Department. After years of steady losses for al-Qaeda–linked groups, Sunni extremist recruitment is rising, aided by private funding networks in the Gulf, particularly in Kuwait, with much of the violence directed at other Muslims rather than Western targets. Shia militant groups are also gaining strength, in part to confront the threat of Sunni extremism. In 2015, the Islamic State claimed responsibility for, among other attacks, bombing Shia worshippers in Kuwait; attacking Sunni and Shia mosques in Saudi Arabia; downing a Russian passenger plane in Egypt, killing over two hundred people; and a pair of suicide bombings in a Shia-majority district of south Beirut that killed more than forty people.

U.S. authorities have warned that the war in Syria, which has attracted thousands of fighters from Europe and the United States, poses a long-term threat to Western security. Islamic State attacks and foiled plots in Europe have put the continent on edge, and the backlash against Muslims and immigrants threatens to end the EU’s open-border policy. 

Saudi Arabia and Iran have deployed considerable resources to proxy battles, especially in Syria, where the stakes are highest. Riyadh closely monitors potential restlessness in its oil-rich eastern provinces, home to its Shia minority, and deployed its forces, along with other Gulf countries, to suppress a largely Shia uprising in Bahrain. It also assembled a coalition of ten Sunni-majority countries, backed by the United States, to fight Houthi rebels in Yemen. The war, fought mostly from the air, has exacted a high civilian toll. Saudi Arabia provides hundreds of millions of dollars in financial support to the predominantly Sunni rebels in Syria, while simultaneously banning cash flows to al-Qaeda and extremist jihadi groups fighting the Assad regime. 

Iran has allocated billions of dollars in aid and loans to prop up Syria’s Alawi-led government and has trained and equipped Shia militants from Afghanistan, Lebanon, and Iraq to fight in Syria. Iran and Saudi Arabia, which have repeatedly postponed efforts to establish a dialogue for settling disputes diplomatically, discussed the conflict in Syria in October 2015 at U.S. urging. This was a notable development though cast into doubt by a rupture in diplomatic relations in early 2016. Both countries have confronted the Islamic State, with Iran fighting it in parts of Iraq, while Saudi Arabia and other Sunni-majority countries back a U.S.-led air campaign against the extremist group in Syria and Iraq.

The ongoing civil war in Syria has displaced millions internally, and more than four million civilians, mostly Sunni, are now refugees in Iraq, Jordan, Lebanon and Turkey. The influx of more than one million mostly Sunni Syrians into Lebanon, a state that experienced its own fifteen-year civil war (1975–90), has burdened its cash-strapped government and put pressure on communities hosting refugees. Jordan and Iraq are struggling to provide housing and services to an impoverished and traumatized population. Turkey has provided considerable humanitarian aid, yet Ankara must increasingly balance “the public’s sympathy for and unease toward refugees,” the International Crisis Group reports. The spillover of migrants and refugees into Europe spiked in 2015, and countries with generous resettlement policies are bracing for a larger influx as the wars in the Middle East continue.

Syria threaten to redraw the map of the Middle East. The Assad regime has consolidated control over Syria’s Mediterranean coast, the capital of Damascus, and the central city of Homs, which together comprise a rump state contiguous with Hezbollah’s strongholds in Lebanon, threatening the territorial integrity of Lebanon. Other parts of the country are contested or controlled by various rebel and Islamist groups, including the Islamic State, which seeks to dominate the eastern regions of Syria that link to its territory in Iraq. And Kurdish groups in northern Syria, which, like their Iraqi cousins, have long campaigned for basic rights denied under the Ba’athist government, are on the verge of gaining de facto independence.

The United States spent more than $1 trillion in Iraq, but the country remains in a precarious state. Sectarian tensions are mounting in Iraq as the newly ascendant Shia majority struggles to accommodate the Sunni and Kurdish minorities while confronting extremist Sunni groups. Yemen, too, which was unified in 1990, is at risk of splintering again. Most politicians and activists in Iraq, Syria, Lebanon, and Yemen reject calls to redraw the map of the region, but the shifting borders and emergence of new areas of influence based on sectarian and ethnic identities are a growing challenge.

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Managing Editor: Robert McMahon
Executive Producer: Jeremy Sherlick
Senior Producer: Hagit Ariav
Assistant Producers: Kevin Lizarazo, Katherine Wise
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