“No brother of mine”: Who started the war between ISIS and Iran?

How it all began

In May 2015, in one of his rare audio addresses, the late Abu Bakr al-Baghdadi voiced his vision of a holy war. According to the self-declared caliph of the self-declared “Islamic State of Iraq and the Levant,” better known by the acronym ISIS: “It would be wrong to believe that the war we are waging is just the war of the ‘Islamic State.’ It is the war of all Muslims, in the vanguard of which is the ‘Islamic State.’ It is the war of Muslims against the infidels.”

At the time, ISIS was at the peak of its territorial conquests, having subjugated nearly half of Syria along with a vast expanse of western Iraq. Even then, however, clouds were gathering over al-Baghdadi's creation. Western countries had assembled a military coalition for a new war in the Middle East. Their planes were already bombing ISIS bases and convoys, while local anti-ISIS forces in Syria and Iraq were increasingly resisting the caliphate's jihadist fighters.

For al-Baghdadi and his associates, the question was no longer one of acquiring new territories, but of finding some means to hold on to what they had already taken. To achieve this, ISIS needed people — people in the form of the very Muslim armies that, as al-Baghdadi expected, would heed his call and rush to join his cause. Only in the “shadow of the caliphate,” proclaimed the ISIS head, would Muslims be free from the lies, violence, and humiliations inflicted by the unbelievers. He knew that, for many of those he addressed, the infidels included not only Christians, Jews, and atheists, but also Shiite Muslims.

The 13th issue of the propaganda magazine Dabiq, a glossy ISIS propaganda project, featured an article on the history of Shiism. Its title was “Know Your Enemy,” and it was illustrated with a portrait of Iranian Supreme Leader Ayatollah Khomeini covered in the crosshairs of a sniper rifle. It left no doubt about ISIS's stance towards Shiites, or towards the largest predominantly Shiite country in the world: Iran.

Sunni vs. Shiite - the crux of the conflict

If we set aside the propaganda aspect of the “Know Your Enemy” article, the jihadists' grievances against Shiites (referred to in the story as “rafidites,” meaning apostates) can be summarized as follows: they are infidels (“kafirs”), they preferred collaboration with Christians over alliances with Sunnis, their leaders forcibly converted Sunnis to Shiism, and those who resisted were killed. The primary sin was considered disbelief, with all other accusations being its consequences. In this context, disbelief does not imply a lack of belief in God – Shiites believe in Allah and worship Him. For many Sunnis, even those less radical than ISIS followers, disbelief primarily signifies a rejection of the fundamental doctrines of Sunni Islam. For Sunnis, a core tenet of the faith involves honoring the first four caliphs, who headed the Muslim community following the death of Prophet Muhammad, and abstaining from any religious practices that were not mainstream in the early years of the religion.

Shiites, on the other hand, consider the first caliphs to have been usurpers. This is their fundamental doctrinal difference from Sunnis. They believe that Allah designated one family to lead the Islamic world until the end of time – the family of Prophet Muhammad's son-in-law, Ali, and his descendants. Shiites hold special reverence for Ali — who became the fourth caliph but soon perished at the hands of enemies — as well as for his descendants, who inherited leadership over the Shiite community. This reverence could not have spread among the first generation of Muslims and is therefore perceived by Sunnis to be a form of dangerous innovation — “bid'ah.” This perception leads a significant part of the Sunni world to deny Shiites the right to even be called Muslims.

Contemporary Shiites emphasize that their ancestors were forced to live for centuries under Sunni rule, where they were marginalized and persecuted by those who did not consider them fellow believers. Even the Fatimid Caliphate, which emerged in the 10th century and was led by Shiites, was not, in the full sense of the term, a Shiite state. Its main territorial holdings were in North Africa, quite far from the spiritual centers of Shiism in Iraq and Iran. The majority of the subjects of the Fatimid caliphs were themselves Sunnis. Moreover, the rulers themselves belonged to a relatively small branch of Shiite Islam — one that was considered to be quite revolutionary even by most orthodox Shiites.

Iran leading the Shiites

The story of Shiism’s transformation from the ideology of a marginal sect into a significant factor in Middle Eastern — and later, global — politics, spans a period from the 16th to the 18th centuries and is not short on blood. The process was initiated by Shah Ismail I, the founder of the ruling Persian Safavid dynasty. He brought under his control almost the entire territory of modern Iran, as well as Azerbaijan, Armenia, and parts of Dagestan. Afterward, Ismail I started the conversion of Iranians to Shiism, as they were still predominantly Sunni at the time.

Historians cite several factors motivating the shah to take such a step. Firstly, he was a fervent Shiite who hated Sunnis and persecuted them relentlessly. Secondly, by converting to a different branch of Islam, he aimed to distance himself from the cultural and political influence of neighboring Sunni countries and peoples, particularly the hostile Ottoman Empire. Lastly, a shared faith distinct from that of its neighbors was intended to consolidate the people, giving them a sense of unity and commonality.

As was promised, there will be blood. Initially, the people under the jurisdiction of Ismail I did not wish to abandon their Sunni identity. Ismail I responded to the resistance of Iranians by destroying mosques, executing preachers, and confiscating Sunnis’ property. His name became synonymous with militant anti-Sunnism and the violent conversion to Shiism.

It is not without some historical basis that the aforementioned ISIS propaganda article portrays Ismail I and his descendants as the literal embodiment of evil. The current Iranian leadership, in the same article, is referred to as the heirs of the Safavids and the continuers of their legacy.

At the same time, the current ruling regime in Iran, led by the Ayatollah, does not formally position itself in opposition to the Sunni world. Its founder, Ayatollah Ruhollah Khomeini, intentionally refrained from mentioning Shiism as the basis of the state ideology. The republic established as a result of the 1979 revolution, which brought Khomeini to power, deliberately termed itself “Islamic” rather than “Shiite.”

However, the country's constitution unequivocally states that only a Shiite can become president, and in the decades since the revolution , no Sunni has held a ministerial position or been appointed as governor or mayor. Sunni literature in the country is practically inaccessible, and the approximately one million Sunnis living in the capital Tehran are forced to make do with just nine prayer rooms, which the authorities loudly declaim qualify as “mosques.”

At issue is not only the way Shiites interact with Sunnis, but also how Sunnis perceive their relations with Shiites, especially when it comes to Shiite dominance. The majority of the world’s Muslims are Sunnis, with all the various Shiite denominations making up no more than a combined 15% of the entire Muslim population on Earth. There are very few countries that have a predominantly Shiite population: Iran, Iraq, and Azerbaijan, whose populations largely converted to Shiism during the time of Ismail I; and, separately, Bahrain.

On the territory of modern Iraq, the Shiite majority was largely disenfranchised for centuries. From 1534-1703, the area was under the control of the Sunni-dominated Ottoman Empire. Between 1704-1831, Sunni Mamluk conquerors ruled the land. Then Ottoman forces returned before ultimately handing over control to the British in 1920 following Constantinople’s defeat in WWI.

It was not only Iraq that came under British control. A League of Nations mandate — a colonial-era administrative mechanism — granted the crown control over a significant part of the Middle East under the. At the time, it was believed that, even if nations like Iraq deserved independence, they still needed to “grow” into fully fledged democracies under the tutelage of the European great powers.

The colonial administration relied on Sunni sheikhs — conservative rural elites willing to collaborate with the British in exchange for maintaining the customary order and preferences they had enjoyed since Ottoman times. They played roles in the lower and middle bureaucracy under the British. All three of Iraq’s kings, who ruled both during the British mandate period and after its end, were Sunnis. Almost all rulers of Iraq following the overthrow of the monarchy in 1958 were also Sunnis (the one exception being General Abdel Karim Kassem, who led the coup that transformed the country from a monarchy into a republic; Kassem's father was Sunni, his mother was Shiite, and Kassem himself demonstratively distanced himself from both denominations).

Saddam Hussein, who ruled the country single-handedly from 1979 to 2003, was a Sunni. He did not trust Shiites: in the Middle East, where religious affiliation often means more than education and connections, and where even political parties are formed based on denominational principles, he could not rely on the complete loyalty of the Shiite majority.

Shiite spiritual and political leaders were imprisoned, sent into exile, disappeared without a trace, or perished under mysterious circumstances. Shiites were prohibited from celebrating their holidays or demonstrating their commitment to their religion in other ways. Therefore, it is not surprising that Iraqi Shiites enthusiastically welcomed the Islamic Revolution in Iran in 1979 and even attempted to replicate the success of their neighbors and co-religionists by initiating their own uprising.

Rushed and poorly prepared, this uprising had no chance of success and was swiftly crushed. However, it demonstrated to the entire Middle East that the Iranian revolution had turned Shiism into a potentially dangerous ideology for Sunni autocrats — dangerous, but controllable so long as these autocrats retained control over the punitive apparatus, courts, and military, with elections absent or manipulated, allowing them to ignore the majority's position.

American contribution to the development of Shiism

All of the above was characteristic of Iraq for decades, right up until the overthrow of Saddam Hussein by the international coalition led by the United States in 2003. It was the end of Hussein’s rule that set in motion the chain of events that eventually led to the emergence of ISIS. The Americans dismantled Iraq’s authoritarian governance system and, after a brief period of rule by a temporary administration appointed from Washington, facilitated Iraq's transition to genuine — if far from perfect — representative democracy.

In this new system, the Sunnis, accustomed to their minority but dominant position, suddenly found themselves obliged to share power with the Shiite majority. This alone would have been enough to fuel a robust anti-Shiite resistance. However, the Sunnis found more substantial reasons for their animosity towards the Shiites.

After Saddam's overthrow, the Americans simply disbanded the Iraqi army and intelligence services, dismissing hundreds of thousands of people. Shiite recruits, viewed by the Americans as natural allies in the fight against Sunni sympathizers of Hussein, were elevated to the ranks of officers and generals. Many of the dismissed personnel went underground, initiating a war against the American presence and Shiite dominance.

As paradoxical as it may seem, Shiite Iran played an active role in financing and arming the Sunni insurgency. In reality though, there is no paradox here. Tehran aimed to incorporate Iraq into its informal empire, which already included financially and politically dependent Syria and Lebanon. Iran’s plans were being hindered by the American military presence in Iraq, and so the Iranians decided to create unbearable conditions for the Americans deployed there, forcing them to leave the country and then moving on to deal with the irregular Sunni groups, presumably less threatening than the U.S. Army, on their own terms. However, things did not go as planned.

Despite the bloody guerrilla war unleashed by the Sunni insurgents, the Americans were not eager to leave Iraq. In response to the surge in violence, U.S. forces carried out mass arrests, detaining anyone suspected of involvement with the insurgency or of aiding guerrillas in prisons and camps. Iraqi former military personnel, officials, and religious preachers found themselves behind bars, where they began to establish connections with each other and exchange ideas. The relationships created between anti-American elements in American-run prisons played a crucial role in the emergence of ISIS.

The persistent American presence also meant that Iran found itself mired in a protracted war of everyone against everyone. Tehran adapted by ceasing its support for the Sunni insurgency and redirecting it towards Iraqi Shiites. The latter were displeased with the prolonged U.S. presence in their country and the fact that the new, albeit predominantly Shiite, government still had to take American interests into consideration when making decisions in Baghdad. Iran's new plan was to provide comprehensive assistance to Shiite groups in the war against both the Americans and the Sunnis.

In 2011, the U.S. armed forces finally withdrew from Iraq, but that did not end the war. The Shiite factions clung to power in part thanks to the overt involvement of Iran. In Iraq, there were no less than a dozen political parties aligned with Tehran, many of which had their own paramilitary organizations directly participating in combat. Iran, almost unabashedly, armed and financed these organizations.

Deprived of their privileged status and constantly facing threats from Shiite groups, Iraqi Sunnis quickly radicalized. They blamed Americans, electoral democracy, and Shiites for their loss of influence. Abu Bakr al-Baghdadi, proclaiming ISIS, pledged that there would be no place for any of the aforementioned infidels in his caliphate.

The blend of contempt for Shiites, hatred for Americans, and disgust for democracy was not something new among Sunnis. However, al-Baghdadi and his followers elevated these grievances to such a level that even Al-Qaeda’s leadership had to offer up public justifications for what ISIS claimed was Osama bin Laden’s radical terrorist group’s excessive leniency towards Shiites.

The ideology of ISIS is fundamentally rooted in the contempt for Shiites. Without dismantling the authoritarian system that practically deprived Shiites of agency, and without Sunnis feeling detached from the ruling caste, ISIS would never have had a chance to vie for popularity among Iraqi Sunnis. Baghdadi's terrorists adeptly played on the emotions of their fellow believers, exploiting a widespread sense of injustice and offering a simple solution to combat it — the total annihilation of their tormentors, once and for all. These tormentors, of course, included Iran.

How will the standoff between Iran and ISIS end?

Both ISIS and Iran consider Iraq to be their territory, and the two rivals vie for the dominant role in the country. Each side has significant support among Iraqis themselves – local Shiites, while not uniformly pro-Iran, often harbor sympathies for Tehran. Among Sunni Arabs, on the other hand, many view jihadists as saviors from the rule of Shiite heretics.

However, the weariness of ordinary Iraqis after decades of war, the modicum of security provided by the return of a few thousand American troops to the country, and the military's allegiance to the state rather than religious factions, have all helped prevent the nation from plunging into a new large-scale conflict.

Additionally, neither ISIS nor Iran has the luxury of focusing their attention on just one adversary. Since its peak in 2014, the terrorist group has lost significant swathes of its former caliphate not to Iranian forces, but primarily to Western-backed Kurds and other groups who do not wish to see their homelands occupied by a medieval death cult. Iran, for its part, is busily supporting its proxy Hamas in the Gaza Strip, busily struggling to combat the increase of U.S. forces and their allies in the Middle East, and busy resisting the continued foreign intervention into the territory of their allied Houthi rebels in Yemen. Diverting attention to hunting down remnants of the self-proclaimed caliphate seems to be a lower priority for the Ayatollahs.

For the decision makers in Tehran, it is more practical to increase funding for their proxy forces in Iraq and to concentrate their real strength on more critical issues for the regime. As for ISIS, it simply lacks the capacity to engage in a fair fight with the Iranian army. Gone are the days when the jihadists boasted vast armies, heavy weaponry, artillery, and billions of dollars. And while they are inclined to give up, engaging in large-scale battles with a substantial nation state is currently beyond their capacity.

All of this means only one thing — ISIS will continue its terrorist war against the Shiite community it despises, but without any real chance of success. Iran, for its part, will remain occupied with more pressing priorities. And even if Tehran were to turn its full proxy force against the former caliphate, it is important to remember that carpet bombing by American aircraft was not enough to wipe out the Islamic State completely. The low-level conflict between ISIS and Iran looks set to continue for the foreseeable future.