ISIS and its sympathizers are dedicated to wiping out the infidels and taking control wherever they can and increasingly this has resulted in them striking soft targets in western Europe because this is all too easy to do and also because - unlike in Hungary and other eastern European countries - there are significant numbers of radicalized indigenous/home grown Muslims to assist them.  

To imagine that they sit around and deliberate on which countries rate a pass in terms of their attacks rather than focusing on promising soft targets with large crowds and enlisting suicide bombers from large indigenous Muslim populations as in western Europe is, I think, highly doubtful.

ISIS and al Qaeda and Boko Haram and several other radical jihadist terrorist groups are beyond reason, negotiation and appeasement.

Churchill put it best when he observed, "An appeaser is one who feeds a crocodile hoping it will eat him last"