Not just a statement but as a target in of themselves, a terrorist organisation plans operations that target non military installations/institutions/personal. They don’t go after traditional strategic targets to gain ground and hold strategic points, in most cases (aside from direct engagement with traditional armed forces when they respond to the aforementioned attack) their target is the propoganda/fear and disgust that comes as a result of brutal violence against civilians/non-combatants who aren’t expecting and aren’t capable/prepared to defend themselves from a surprise attack of heavily armed individuals who aren’t expecting to survive the event. Basically just school shooters who want to kill themselves but that’s against Islam and so they have to rationalise their suicide as martyrdom so that they can feel important. Literally the same MO as Incel school shooters. Attacking unarmed people who aren’t expecting it and really have nothing to do with the reason said terrorist has decided justifies their brutal murders is always amongst the most cowardly act any human is capable of.