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.