A year on, no quick fix to halt ISIS 'caliphate'

A year after its establishment, the Islamic State group's self-declared "caliphate" in Syria and Iraq remains well-funded and heavily armed, and experts say it could be around for years to come.

The would-be state headed by IS chief Abu Bakr al-Baghdadi -- called Caliph Ibrahim by his followers -- has suffered setbacks in the months since it was proclaimed.

A US-led coalition is carrying out strikes against the group throughout its territory and this week it lost the key Syrian border town of Tal Abyad to Kurdish forces.

But the group has continued to score shocking victories elsewhere, including the seizure of Syria's ancient city of Palmyra, and experts say IS and its "caliphate" have the means to last for years.

"The group operates as an insurgency and might shrink in one region and expand in another, but it'll stay with us for the foreseeable future," said Hassan Hassan, associate fellow at the Chatham House think tank's Middle East and North Africa programme.

"I see it existing and active for at least a decade."

Other experts agree that while the current borders of the caliphate are likely to shift, the entity is far from on its last legs.

"The very idea of the caliphate and 'Caliph Ibrahim' will surely remain for many of the movement's members and supporters around the world," said Charles Lister, a vising fellow at the Brookings Doha Center think thank.

IS's success is driven by various factors, chief among them its significant financial resources, superior firepower, and ability to play on the legitimate grievances of local populations in Syria and Iraq.