- the recent bombing in Paris was known to happen, there can't be such huge influx of refugees without some terrorist sleeper agents being injected
- European countries were morally obliged to accept refugees, as most of them are civilians with nowhere to go
- any government strives to protect its citizens and the state's international interests.
Based on the above, I can imagine the following situation. The president and defence minister agree on the course of action. Psychological profiles are researched among the special forces, without the scientist knowing exactly why. The single soldier, who is most probable to keep a secret is selected. He enters a restaurants and opens fire on the personnel. 4-5 people die. The police knows nothing of this, but our guy very well trained and could be receiving help from above.
Result: 5 people die, instead of 160 and the country has reasons to close its borders. Why was this a bad idea?