I won’t belabor the details of the Christmas market truck attack in Berlin, but the very latest story includes the shooting of the prime suspect in Italy and the arrest of three more suspects in Tunisia, CNN story here. Both the original (incorrect) first suspect and then the perpetrator had apparently hidden as “asylum seekers”, later turned down.
There’s no question that Trump can try to make a lot of this as to how asylum seekers will be treated in the U.S. In "retaliation" ISIS has apparently "published" a list of religious targets in the US, a list which the FBI says is very old and riddled with misspellings and errors.
Michael Birnbaum has a grim front page article in the Washington Post, that for Europe, religious or “resentment” terrorism may be a “fact of life” for decades.
As for internet recruiting, the Washington Post has pointed out terror groups are using the permissive dark web app “Telegram”) story by Joby Warrick. Young men with petty criminal records and an inability to "get" modern life seem to be particularly drawn to the "brotherhood" of religious cultism.