The premise was framed all wrong. OF COURSE the terrorists are infiltrating the refugee stream from Syria, and exhibiting some of their worst terrorist behavior while in the transition - murdering and raping the widows, children, unaccompanied females, and lesser Muslims or non-Muslims all along the way, then disposing of these victims by throwing them overboard while at sea, or left for dead along the trek.
Plus whatever small arms or contraband they are smuggling at the same time.
Somebody should probably ask Russell Berman if he thinks fish can swim.