Then there is the historic mis-handling of relations with Turkey. 

If Turkey were part of the EU (e.g., since 1983)  this would never have happened.  But Islamophobia and consequent bad-faith bargaining have always kept Turkey out of the EU.

The chickens have come home to roost.  Not only is Turkey not safely part of the EU,  but in 2016 it effectively ceased to be a democracy, and is now a fascist dictatorship in all but name.

How Turkey can remain in NATO very much longer is hard to understand.  While not a humanitarian disaster on the scale of Syria (not yet, anyhow), this is at least as large a defeat for western foreign policy as the failure to unseat Assad.

Like Germany in the EU, If Turkey had taken a more thoughtful approach to its Kurdish minority, Turkey could have been the local regional economic engine surrounded by economic satellites and allies in Mesopotamia, Kurdistan, Jordan, Lebanon, Syria, and maybe even Israel - to everyone's benefit.

Oh, what might have been.