Common Sense: Lone wolves
The new horror in France was orchestrated by a French citizen not claimed initially by any particular terrorist group. And in that the dangers of the world have been magnified many fold.
This act of terrorism was by what is often called a lone wolf, an individual just as extreme, no less insane then those who are part of the many international terrorist groups, but in a sense more dangerous because such people are much more difficult to identify before they act.
The open border policies of the European Union combined with historic ties with former colonial possessions are really coming back to make Europe, and in particular France and Belgium, very dangerous places. Frankly, I do not think either country can guarantee the safety of any one within its borders.