No consensus on caliphate

The first victims have been nailed to crosses, marking the start of the ISIS jihadist group's reign in the caliphate - an Islamic state headed by a supreme leader - they believe to have established.

Women now need to cover their bodies completely in public. Restaurant owners may not sell alcohol or offer cigarettes to guests. They are also not allowed to play music or show FIFA World Cup broadcasts on television. If they break any of these rules, they risk corporal punishment.

Many people in Iraq now need to adapt to life under a hard-line sharia regime. The caliphate is to extend from the Aleppo region in northern Syria to the Iraqi province of Diyala in eastern Iraq, according to a statement by ISIS (Islamic State in Iraq and Syria) spokesman Abu Mohammed al-Adnani.

The group has also changed its name to reflect this plan: it now calls itself Islamic State. The "caliph" of the new order is ISIS leader Abu Bakr al-Baghdadi. The Islamic state has been hailed as "the dream in all Muslims' hearts" and "the hope of all jihadists."

Vanquishing national borders

According to Stephan Rosiny from the German Institute of Global and Area Studies (GIGA), the caliphate concept does have a large appeal for many Muslims in the region. The religious qualities that ISIS claims to embody are attractive to like-minded people. "In short, the radical Islamists are promising that yes, Islam is the solution to everything," said Rosiny.

And the region is plagued with many problems that need to be solved - this extends the ISIS's appeal beyond the religious aspect. According to Rosiny, the group is supporting Iraqi Sunnis in their efforts to secure their place in Iraq's politics and society.

Since the fall of Saddam Hussein and in particular since Prime Minister Nouri al-Maliki, a Shiite, took office, many Sunni Muslims in Iraq have felt politically and socially excluded. This feeling led to protests in the country's northwest, which were exploited by ISIS for its cause.

After ISIS established itself in Mosul and other cities, is started announcing its greater plans. One of them is to repeal the Sykes-Picot Agreement of 1916, which divided the territories of the Ottoman Empire into spheres of British and French influence. The accord led to the marking out of arbitrary borders that broke up the region into several states.

"The promise to dissolve these borders was first made in the 20th century by pan-Arab nationalists and then by moderate Islamists," said Rosiny. "Neither group has fulfilled it. Now the radial jihadists aim to reach the goal."

Little political consensus

However, it is exactly these ambitions that could cast doubt on ISIS's continued success. The group - which consists of tribal warriors, former Saddam Hussein supporters, Sunni Islamists and radical jihadists - was originally held together by a common goal: overthrowing the government of Nouri al-Maliki. But not all groups within the ISIS would necessarily support the vision of a cross-border caliphate.

"It would be nearly impossible for ISIS to establish or maintain their caliphate over a large territory, as their version of Islam is very different from that of other Sunnis in the captured areas," explained Rosiny.

Before anything else, there is the question of how such a caliphate could be established in the first place. Neither its government nor its borders are legitimate, which prevents it from being internationally recognized. It would most likely have a difficult economic and political future. Internationally isolated, it would have to be fully self-reliant.

Not all in favor of caliphate

This is why not all ISIS members are dancing to the tune of the master plan. Even some of the other jihadist groups are not in favor of vanquishing Iraq's current borders. The Ansar al-Sunna group, for example, supports the establishment of a caliphate but within Iraq. The Iraqi Muslim Brotherhood, meanwhile, hopes for a province that is independent of Baghdad in terms of the military, the judiciary and the economy, but without severing ties completely.

Other groups, such as the Islamic Army, are advocating Sunni religious and cultural sovereignty within Iraqi borders. They have been aided by former members of the Sunni-dominated Ba'ath regime, who hope to one day restore the party to its former glory. Due to its nationalist stance, the Ba'ath supporters would not be in favor of a regional caliphate.

Opposition to al-Maliki's government is the only position that all ISIS-affiliated groups have in common. The conquests of the recent months could already be too much for some of them. In the future, ISIS will need to look for new alliances. And even if it does not manage to establish a greater sphere of influence, many Iraqis fear that the group will still have enough power to continue its reign for some time yet.