The Finnish Defence Forces (FDF) has flown F/A-18 Hornet fighter jets over densely populated areas of southern Finland in recent days following Ukrainian attacks on Russian oil ports across the Gulf of Finland.
Military aircraft were heard over the Uusimaa region, which includes Helsinki, on Thursday afternoon and overnight into Friday.
"This is due to Ukrainian activities in the areas surrounding Finland. They are there to ensure that drones do not stray into Finland. At the same time, we are also monitoring the area to ensure that we know what is happening there," the FDF told Yle on Friday morning.
The FDF said it had "intensified surveillance and measures to ensure territorial integrity when Ukraine carried out attacks against Russian targets in the eastern Gulf of Finland".
"These activities may be particularly visible in southwestern Finland and over the eastern Gulf of Finland, as Air Force fighter aircraft and Navy readiness vessels carry out their missions," the FDF said in a separate press release.
On Wednesday, Ukrainian drones damaged an icebreaker and an old Finnish building in Vyborg, some 40 kilometres from Finland's eastern border.
Smoke visible from Finland
On Wednesday, Russia's Baltic ports of Ust-Luga and Primorsk suspended loading of oil products, sources told Reuters, after Ukrainian drone attacks sparked blazes, with smoke visible from Finland. Ukraine's SBU security service said its drones had flown over 900km to strike the Ust-Luga terminal.
Primorsk resumed oil and fuel loadings on Thursday, though at lower capacity than normal because of damage to its infrastructure. Primorsk, known as Koivisto in Finnish, was part of Finland from roughly 1917 to 1944.
Worst-ever disruption of Russian oil exports
Reuters estimates that at least 40 percent of Russia's oil export capacity had been halted as a result of the Ukrainian drone attacks, an attack on a major pipeline, and the seizure of tankers.
The shutdown is the most severe oil supply disruption in the modern history of Russia, the world's second-largest oil exporter.
President Volodymyr Zelensky told Reuters late Wednesday that Ukraine is using long-range strikes on energy infrastructure to maintain pressure on Russia after US President Donald Trump eased oil sanctions on Moscow in an effort to lower petrol prices during the Iran war, which began nearly a month ago.
Ukraine's European allies, who want to maintain pressure on Russia to end its four-year-old war, have criticised the move by Washington.
