This reinforces my opinion that it's a good idea to restrict warfare to state actors and make it a criminal offense to join armed movements in foreign countries

This reinforces my opinion that it's a good idea to restrict warfare to state actors and make it a criminal offense to join armed movements in foreign countries. I have a lot of sympathy for Kurds in their struggle for a nation of their own, but having members of the public travel from European countries to fight for or against Daesh, be indoctrinated to kill, and then return to Europe carrying both the technical learnings of warfare, the ideological baggage collected, and the emotional trauma of war, can lead to further atrocities in Europe. Armies of governments aren't all good and nice, but they do have more restrictions on what they can and will do, compared to ad hoc militias - and more follow-up of how former service members are doing.