The rise of Isis is rooted in a mix of politics, a Sunni sense of isolation and a shakeup in Salafist doctrine. Here, an analyst whose Syrian home has seen some of its bloodiest excesses, explains its dramatic surge

Abu al-Mutasim, 18, from a Syrian border town in the province of Deir Ezzor, joined the rebellion against the regime of President Bashar al-Assad in early 2012. He left his family home in Bahrain, where his parents worked, and fought for the Free Syrian Army for a few months before joining the hardline group Ahrar al-Sham. Around the end of the year, disillusioned, he went to visit his family. His parents banned him from travelling back to Syria. But last summer he returned to join the Islamic State in Iraq and Syria (Isis), now renamed the Islamic State.

I asked him what he would do if his father were a member of Jabhat al-Nusra, al-Qaida's official franchise in Syria, and the two met in a battle. "I would kill him," he replied firmly. "Abu Ubaida [a prophet's companion] killed his father in battle." What drives people such as al-Mutasim? I faced this question directly recently, as I saw Deir Ezzor, the province where I too come from, overrun by Isis, and as the group carried out some of the Syrian conflict's grisliest atrocities.

Isis, a Salafi jihadist force, evolved out of a group founded by Abu Musab al-Zarqawi, a Jordanian militant who moved to Iraq after the US invasion of Afghanistan in 2002. He later launched al-Qaida in Iraq, responsible for the bombing of the Askari mosque in Samarra that triggered Iraq's 2006-07 civil war. Renamed the Islamic State in Iraq after its leader was killed in a US raid in 2006, it was weakened in 2007 after US forces aligned with Sunni Iraqi tribes to fight the group.

The Syrian conflict revived Isis, which provided support to one of its members, Abu Mohammed al-Jaulani, to form a group in Syria after the 2011 uprising. In April 2013 the group's current leader, Abu Bakr al-Baghdadi, announced a merger between his group and Jabhat al-Nusra, under the name of Islamic State in Iraq and Syria. The merger was rejected by Jabhat al-Nusra and most of its foreign jihadists then defected to Isis. Since then Isis has been at war with Syrian rebels to impose itself as a state that accepts no other group acting in rebel-held areas unless they pledge allegiance to it. On 29 June, on the first day of Ramadan, Isis announced that al-Baghdadi was "elected" by the Shura Council as a caliph for all Muslims, and changed its name to the Islamic State.

Peshmergas and Kurds show readiness to fight Isis on streets of Irbil in northern Iraq. Photograph: Vianney LE CAER/SIPA/REX

Deir Ezzor is the fifth province in Iraq and Syria so far to experience the group's model of governance, a strategy so extreme that al-Qaida formally disavowed the group in February. Isis's first wave of sweeping victories was in the Sunni provinces of Nineveh and Salaheddin in June. It then benefited from the massive stockpiles of weapons it captured, as well as the momentum it gained in morale and fear, to conquer new areas in Syria, often with little resistance. After taking over Deir Ezzor, the group is now advancing northwards in the Aleppo countryside.

From a military perspective, Isis thrived on the disunity of the Syrian rebels and the inconsistencies of their backers. When al-Baghdadi announced the merger between his group in Iraq and Jabhat al-Nusra, the group started to act as a state in rebel-held areas. Despite its low numbers, Isis established a reign of terror in many areas across Syria. It alienated most of the rebel groups by creating smothering checkpoints, confiscating weapons and imposing its ideology on the local population, something Jabhat al-Nusra had avoided. By the end of last year, all rebel groups declared war against Isis and drove it out of Idlib, most of Aleppo and Deir Ezzor. But the war cost the rebels a lot: around 7,000 people were killed in the battles against Isis and the main rebel coalitions started to disintegrate as a result of the fighting. The Islamic Front, once the most powerful rebel coalition, is now a shell of its former self. Jabhat al-Nusra, once the most effective rebel group, is struggling to halt the drifting of its fighters or sympathisers to Isis, especially after it lost its stronghold in Deir Ezzor.

The disintegration of these groups was accelerated by the fact that many of their rank and file, as well as commanders, either sympathised with Isis or were reluctant to direct their guns to any party other than the Syrian regime. After all, groups such as Ahrar al-Sham had links to al-Qaida and held similar views to Isis, even if their leaders disputed with Isis over territories.

In this context of rebel exhaustion, the latest comeback of Isis promises to endure. Before the group committed its latest massacres in Deir Ezzor, for example, it had imposed a state of calm welcomed by residents, who had been alienated by militia control over the region's lucrative resources. When Isis came in, it subdued these militias and, according to sources, it intends to distribute oil revenues to provide services and start development projects, such as fixing bridges, providing clean water and establishing irrigation projects. One resident told me: "The area has never been safer in months and we no longer hear gunshots because rebel infighting stopped. Everyone swore allegiance to Isis or fled if they had made money from the oilfields."

A US F-16 warplane prepares to land at Incirlik air base, southern Turkey. Isis has controlled many villages near the Turkish border. Photograph: Tarik Tinazay/AFP/Getty Images

The avalanche of Isis is powerful and it is not difficult to see that worse is still to come. Beyond these military and practical factors, it is important to view the Isis phenomenon as part of two wider trends within Sunni Islam that will make Isis a long-term ideological menace, even if it is reined in militarily.

First, the rise of Isis should be seen in the context of the Sunni sense of alienation that is common, particularly in the region from Lebanon to Yemen and from Egypt to Iran. This sense of ejection, or injustice, is known in Arabic as "madhloumiya", a concept historically associated with Shias. Noticeably, Sunnis throughout this part of the region behave as a minority: paranoid, insecure and under siege. Shias are more decisive, confident and organised. Shias – with Iranian backing to militias in Iraq, Lebanon and the Arabian peninsula – are ever more vocal and active. For the first time in history, Shia fighters cross borders to fight in jihad, as happened in Syria under the pretext of protecting Shia shrines. Sunnis, by comparison, feel they are under attack, with no defenders. The idea that fighting is the only way to get their rights is gaining in attraction. Even though the group that is doing the fighting is vicious, some believe this is a price that has to be paid before forming formidable militias to act as Sunnis' line of defence, given the fact that Shia militias behaved in a similar way during the Iraqi civil war. Sunnis' traditional powerhouses, whether political or religious, are perceived as standing with the oppressors, completely discredited or silent.

Isis emerges out of this desperate situation with the potential to fill this vacuum. This attitude can be discerned from the fact that clerics across the regime have responded feebly to the atrocities committed by Isis and that its seizure of Sunni provinces in Iraq was widely celebrated. There is concern among some governments in the region that Isis has sympathisers within the religious establishment. King Abdullah bin Abdulaziz of Saudi Arabia, for example, recently criticised the "silence and laziness" of the ulema, or body of Muslim scholars, in speaking out against Isis extremism. His public scolding of the top ulema, aired on national television, was unprecedented.

The second trend that makes Isis a more perilous phenomenon is the neglected ideological shakeup of Sunni Islam's traditional Salafism. This has been taking place more noticeably since the Arab spring, when Salafis became increasingly politicised. Salafism, not to be conflated with Wahhabism, was traditionally inward-looking and loyal to the political establishment. Salafists, religiously speaking, hold extremist views, but also tend to hold pragmatic political positions. Jihadists, who are heavily influenced by Salafi ideas but equally influenced by political Islam, started polarising the Salafi landscape and steadily, if slowly, eroding traditional Salafism.

A fighter from the Islamist Syrian rebel group Jabhat al-Nusra poses at a checkpoint in Aleppo. Isis is still steadily advancing in Syria. Photograph: Reuters

Besides Isis, one movement that illustrates this trend is a Salafi-Brotherhood hybrid known as Sururiyya. The movement was founded in the 1980s in Saudi Arabia by a former member of the Syrian Muslim Brotherhood, who became influenced by Wahhabism. In a recent interview, Mohammed Surur Zain al-Abidin told the pan-Arab newspaper Al Quds Al Arabi that his movement had turned Salafism upside down and led from one world view to another.

Because revolutionary groups such as Sururiyya and Isis derive their religious concepts almost exclusively from Salafism, they are invigorating, polarising and animating Salafism. They are also drawing mainstream Sunnis who objected to Salafists' practices, such as the blind obedience to rulers.

Isis is not a disease. It is a symptom – of a political vacuum, a sense of rejection among Sunnis, and an ideological shakeup within Salafism. It is important to emphasise, however, that there are grounds for optimism. While the strength and appeal of Isis should not be underestimated, its rise has triggered a unique debate in the region.

Since Isis took over large swaths of Iraq, in particular, Arabic media outlets of all types have produced reports about the nature of the group and the source of its ideology. There is a collective soul-searching in the region, coming from everyone from ordinary people to clerics and intellectuals. After the 9/11 attacks, such questions came from outside the region and were shunned as "imperialist" or "orientalist". Today the voices are coming from within and are more powerful. Supporters of the group seek to ground its behaviour in Islamic traditions and object to the notion that its atrocities are anomalies.

But its critics have responded. Mohammed Habash, a cleric from Syria, places blame for the rise of Isis on mosque imams, saying: "We did not speak about the caliphate as a political system that is fallible. No, we spoke about it as a sacred symbol of unity … Isis did not arrive from Mars; it is a natural product of our retrograde discourse." A Saudi commentator, Ibrahim al-Shaalan, tweeted that Isis is "but an epitome of what we've studied in our school curriculum. If the curriculum is sound, then Isis is right, and if it is wrong, then who bears responsibility?"

Such a debate is likely to lead to a positive change, but what about people such as Abu al-Mutasim and their victims? The factors that led to the rise of Isis are still unaddressed, while the group has not even reached half of its potential.

Hassan Hassan is an analyst at the Delma Institute, a research centre in Abu Dhabi, and a columnist for the National newspaper. Follow him on Twitter @hxhassan

What the jihadist movement means for the region



Syria

Isis is still steadily advancing in Syria, most recently in the Aleppo countryside. It has eliminated any possibility of a coordinated war against it in territories under control while advancing in areas such as Aleppo, where the rebels cannot dedicate all their resources to fighting it as they are fighting the regime. But the rebels still outnumber Isis and communities in some areas are deeply angered by Isis's random killings.

Turkey

Isis has controlled many villages near the Turkish border and is soon expected to control key border crossings, posing profound challenges for Turkish authorities, whom Isis consider un-Islamic. This may prompt Turkey, a Nato member, to take steps towards closing its borders from the Syrian side.

Jordan

Jordan has historically produced global jihad leaders – Isis evolved out of a group founded by Jordanian militant Abu Musab al-Zarqawi – and the Syrian conflict next door has galvanised a new generation of jihadists that will pose a challenge to the Jordanian authorities as the Syrian conflict continues.

Iraq

After Iraqi forces chose a new prime minister designate, Haider al-Abadi, to replace Nouri al-Maliki, the new government's priority will be to work with Sunni tribes to fight Isis. Although Sunnis have made it clear that they dislike Isis, it will be extremely hard for such a coalition to work effectively, because Isis has been preparing for this eventuality and because American military and advisory help will be crucial, as in 2007.

Kurdistan

Isis's takeover of Sunni areas bordering the Kurdish region pushed the Kurds to annex oil-rich Kirkuk and move closer to independence from Iraq. The move has been thwarted by Isis advances into the Kurdish region as the US made military aid a condition of abandoning these aspirations. But the Kurds are ever more independent from Baghdad, which could be replicated in Syria, where the Kurds have battled Isis for months.

Kuwait

Even before the Syrian uprising, jihadist groups in Iraq and elsewhere benefited from Kuwait's relaxed rules on money transfer for funding. On 6 August, the US Treasury imposed sanctions on at least two Kuwaitis for helping finance extremist groups including Jabhat al-Nusra.