The group capitalizes on the Syrian civil war to exploit the country's oil wealth and stabilize a functioning, if harsh, theocracy.
On June 5, 2014, the Islamic State launched a major offensive against the Iraqi government. Its forces attacked Samarra, seized Mosul and then Tikrit. By the end of the month, Baghdad had lost control over much of its border with Syria. A defining moment came on June 29, 2014, when ISIS filmed the destruction of a border crossing between Syria and Iraq.
The video released to mark the occasion, replete with shots of police buildings being blown up and ruined army vehicles, had a telling title: "The End of Sykes-Picot" – the 1916 agreement that divided the Middle East into spheres of British and French influence.
A key Islamic State principle is the refusal to recognize such national borders. Although the group began fighting in Syria with the aim of overthrowing Bashar Assad’s regime, its ambitions soon far eclipsed that.
The more territory it seized in Syria, the greater its claim to be a genuine Islamic state, a successor to the caliphates of old.
ISIS chief Abu Bakr al-Baghdadi has demanded that all Muslims everywhere, not just in areas under his control, swear allegiance to him as the emir (leader) of the new caliphate. In theory – or at least according to maps shared online by its supporters – the Islamic State seeks to expand its dominion over the entire Middle East, as well as parts of North Africa, Asia and Europe. For now, its legitimacy stands on its ability to consolidate absolute power in the territory under its control.
The Syrian civil war and the ensuing power vacuum provided fertile ground for the Islamic State to grow. Sparked by peaceful demonstrations against the Assad regime in March 2011 in the southern city of Daraa, protests expanded across the country.
Amid growing violence, the uprising became more than just a movement in opposition to Assad’s authoritarian rule. Clear sectarian divisions emerged between the country’s Sunni majority and the ruling elite drawn from the Alawite sect.
Islamist radicals outnumbered the secular moderates and neighboring countries were drawn into the conflict. Iran backs Assad and provides military support through Hezbollah and other militias, while the Gulf states back Sunni rebel groups. Attempts by the international community to broker peace talks have barely gotten off the ground.
The Islamic State capitalized on the power vacuum in Syria to build its power base. The country has also been a major source of wealth. ISIS draws huge funds from the oil fields in areas it seized in the east, with daily revenues estimated at $3 million from black market sales of 44,000 barrels. Through middlemen, the oil is sold to buyers in Turkey, Jordan and Iran.
Since March 2013, the Islamic State's de facto capital has been the northern Syrian city of Raqqa, some 160 kilometers east of Aleppo. With a population of about 1 million people, it was the first major city to fall under ISIS control and has been a benchmark for the group's project to combine harsh Islamic jurisprudence with the provision of basic social services.
Despite the harshness of Islamic State rule, some locals call the relative stability its forces have brought a welcome relief after the utter chaos of civil war.
In Raqqa, for instance, there is electricity for at least a couple of hours a day. Taxes are paid, the schools function – albeit with a curriculum that stretches solely to Islamic studies – and there are even Islamic State traffic police.
The justice system works, although it is extremely brutal. Prayer time is strictly enforced, with all shops and businesses forced to close five times a day.
Smoking and of course drinking alcohol have been outlawed, and a strict dress code has been imposed for both men and women, who must be completely veiled in black, including black gloves. Crime rates are low, perhaps unsurprisingly given the draconian punishments for even minor misdemeanors.
This semblance of providing services is an important propaganda tool for ISIS to shore up its claims to be a properly functioning state.
But this is accompanied by massive human rights violations including summary executions and torture. Dissent runs the risk of death.
Also, information smuggled out by groups such as citizen journalists Raqqa Is Being Slaughtered Silently indicate grave shortages of food and medicine.
The Islamic State now controls about a third of the country, but its authority has not gone unchallenged. It has long been estranged from its former ally the Nusra Front, an Al-Qaida affiliate, and since January 2014, ISIS has been targeted by a coalition of opposition groups, with Western-backed forces and other Islamist groups forming an uneasy alliance.
The Assad government, for its part, has taken a matter-of-fact approach. The Islamic State has clashed directly with Assad’s troops, for instance in the central province of Homs, where the group seized control of the Jazal oil field in September 2015.
But the regime has long been said to buy fuel from the oil facilities the Islamic State controls, and sources cite an apparent informal nonaggression pact between Damascus and ISIS, with regime airstrikes focusing on areas controlled by the Free Syria Army and other opposition groups.
The Assad regime knows that the fear the Islamic State inspires in the international community bolsters its position as a self-declared source of stability.
ISIS is also consolidating its control over the north of the province of Aleppo, a key logistical area because of the road link to Turkey.
The group does not seem terribly bothered by Russia’s military intervention on behalf of the regime, which began in September 2015.
Soon after Russian operations started, the U.S. State Department claimed that 90 percent of the airstrikes targeted the moderate opposition rather than the Islamic State or Al-Qaida-linked groups.