The repeated attacks, heavy immigration of refugees...I'm hoping for the best, but I feel like there is a powder keg here. Whether or not it is based in any fact, how this is handled and plays out is a serious concern.
What do people think the refugees were running away from? Exactly these people.
I think a major problem is that even they can't know who among them - in the big groups of refugees making the journey - is an isis member or supporter, and even if they're not, there's no telling who is going to radicalise in the future. The attacks earlier this year in paris weren't done by someone that came from that area, iirc.
Refugees carry little more than their shirts in their travels. Those guns and grenades didn't come with refugees. End of story.
Guns and grenades are not that hard to get, even in Europe. The limiting factor is how many people are willing to lay siege to a concert hall and calmly execute a hundred people, and whether some of those people were let in under the guise of "refugees".