The war in Ukraine has been quietly creeping into central and western Europe for years - through gas pipeline explosions, cyberattacks, aircraft incidents. But when a rocket-propelled sea drone with 300 kilograms of explosives and its engine still running washes up in a cave at the Greek resort of Lefkada, something changes. Greece reacted out loud for the first time.

The Greek foreign minister Giorgos Gerapetritis issued a sharp warning to Kyiv: "The transformation of the Mediterranean into a theatre of military operations will not be tolerated. Greece will ensure that the Mediterranean remains untouched by military activity." In diplomatic language, the sentence means one thing - it is reaching us too, and it is reaching us now.

The drone, about five metres long, was found by local fishermen in a protected cave on the shore. Experts from the Greek army determined that it is a "Magura V5" or "Mamai" model - Ukrainian sea drones used en masse to attack Russian ships in the Black Sea. With 300 kilograms of explosives, they are not small. They sink tankers.

Kyiv hesitates and claims there is "no record of such a vessel." Sound familiar? It is the standard line in moments when answers are seen as too costly. The Greek military investigation is focusing on two hypotheses: launch from a commercial ship, or from a base in Libya. Data analysis has shown that the location where the drone was found had been preprogrammed as a "safe location" - a detail that says a lot about the operational discipline behind the story.

The Greek authorities believe the drone was meant to attack Russian tankers from the so-called "shadow fleet" - ships that carry Russian crude oil without an official registration in Western registries, across the Mediterranean to third-party destinations. Why would Lefkada matter in that calculation? Because from there, it is not far to the key shipping lanes. And because Greek territorial waters are already being used as a passive part of a war that is being waged without a formal declaration.

For Balkan readers, the question is simple. If Greece, a member of NATO and the EU, has to defend its territory from drones sent by a warring side it sympathises with, what happens to us, who are not in either of those alliances in that form? And how does a country react when war comes to its doorstep - not as a declaration, but as a five-metre submersible with a gun on the porch? Lefkada gave us an answer. Quiet. Diplomatic. But with very little room for ambiguity.