“The Islamic State, or Daesh, once again showed its ability to surprise observers by its swift capturing of the Iraqi provincial capital of Anbar, Ramadi. But should it have been a surprise? Arguably, no. Should we be surprised by further moves by Daesh to continue to extend the reach of their self-proclaimed Caliphate? The answer, again, has to be no.
Why is this the case? Firstly, as has been well-documented, the very DNA of Daesh is built upon consolidating its hold on territory already under its dominion, and to expand the Caliphate in an ever-growing initiative that would, at its end, be global in scope. The leader of Daesh, Abu Bakr al-Baghdadi, is clearly some way off achieving this final aim but, for now, he has plenty of opportunities to continue his strategy of expansionism in the chaotic world that is the present-day Middle East.”
https://www.rusi.org/analysis/commentary/ref:C555B4CB37F241/#.VVuKtJOrHSj
IR Theory & Practice 