[Quarrelsome]

well let us state that given the friendliness between Turkey and Russia despite the arguably staged assassination that they're either conveniently pulling in the same direction or perhaps batting for the same team.

So we can point the attack at the party potentially standing to gain from EU disruption (Russia) or at Turkey itself. Probably the most dull argument (aka most likely to be true) is that this is the work of an enthusiastic member of Erdogan's fanbase.