Finland's military said on Thursday that its forces had detected "a strike" on a Russian warship in the Baltic Sea a day earlier, but insisted the security situation in the area remained stable. It was not immediately clear whether there were any casualties or what had caused the strike. The Finnish Defence Forces, in an emailed statement to Reuters, said they had detected the strike in the Gulf of Finland area and had monitored the development of the situation, adding that Finland was not under any immediate military threat. The defence forces declined to give further details about the location or timing of the incident, or how it was detected.

Estonian media reported on Thursday that the vessel was a small Russian navy ship and that it later returned to St. Petersburg. The Gulf of Finland, a narrow arm of the Baltic Sea between Finland and Estonia, extends eastwards to St. Petersburg, placing the incident close to the Russian city.S1S2

The incident comes amid a wider spillover concern. Ukraine has been sending waves of military drones toward Russia's northwest Leningrad region, which includes St. Petersburg and the Baltic Sea port of Ust-Luga, a major export outlet for commodities such as oil and grain. Some Ukrainian drones have strayed into the airspace of Finland and the Baltic region, fuelling fears that the war is spilling over into NATO countries that border Russia and its ally Belarus.S1S2

Estonia, Latvia and Lithuania issued warnings early on Wednesday telling citizens to take shelter because of drones in their airspace, and NATO scrambled warplanes in response.S1S2