14 November 2014 By Frank Gardner BBC security correspondent
The leadership of Islamic State (IS) has no intention of standing still.
In a 17-minute audio message, purportedly from its elusive leader Abu Bakr al-Baghdadi, the group sets its sights firmly on Saudi Arabia, birthplace of Islam and the world's largest oil producer and exporter.
The speaker does not refer to it as Saudi Arabia, since this is a name derived from the ruling tribe, the al-Saud, whose authority IS does not accept.
Instead he calls it "the land of Haramayn", the land of the two holy places, meaning Mecca and Medina.