A group of German journalism students investigated the drone sightings over military installations in Western Europe and in one instance tracked it back to three commercial vessels belonging to Russian services. The cargo ships involved are the "Lauga", "HAV Dolphin" and "HAV Snapper". The vessels were caught with drones circling over them and showing most unusual movements.
Full report here:
https://www.digitaldigging.org/p/they-droned-back?hide_intro_popup=true
