In mid-August, the Air Force barracks in Cologne-Wahn were briefly closed. The Bundeswehr feared that the drinking water was contaminated. However, the suspicion of an act of sabotage was not confirmed. Nevertheless, fears of possible hybrid attacks of this kind are growing. In Finland, there were a series of break-ins at waterworks in the summer. Finnish security expert Minna Ålander explains why Europe needs to pay more attention to this „gray zone aggression“.