FILE PHOTO: A police officer stands below as firefighters work on the destroyed roof of a house, after Russian drones violated Polish airspace during an attack on Ukraine, with some being shot down by Poland with the backing from its NATO allies, in Wyryki-Wola, Lublin Voivodeship, Poland, September 10, 2025. REUTERS/Kacper Pempel/File Photo

By Tom Balmforth

UNITED NATIONS (Reuters) -Russia deliberately flew drones into the airspace of NATO member Poland this month to test the alliance's response, stoke fatigue in member states with its war on Ukraine and step up pressure on the West, the Ukrainian military spy agency said on Friday.

It sent the written assessment to Reuters after NATO jets downed Russian drones that entered Polish airspace on September 9-10. This week unidentified drones shut down air traffic in parts of Denmark.

The assessment only addressed the incident in Poland.

"Such hybrid operations likely aim to increase pressure on Ukraine's Western partners, potentially leading to: Reduced support for Ukraine, especially military aid," the agency wrote.

Russia denies it planned to target anything in Poland with drones as it was attacking neighbouring Ukraine. U.S. President Donald Trump said in the immediate aftermath that it was possible the drones had ended up there by mistake.

Ukraine uses jamming and electronic systems to try to suppress and divert incoming Russian drone and missile strikes, but the Ukrainian spy agency said it had ruled that out as the cause.

"UAVs (drones) entered Poland not only from Ukraine but also from Belarus. Some UAVs penetrated up to 100 km (60 miles) into Polish territory, far beyond the range of Ukrainian electronic warfare systems," it said.

It also pointed to the large number of drones - around 20, it estimated - involved in the incident. The models included the Gerbera decoy drone, the use of which indicated that Russia had not intended to hit anything, the Ukrainian agency said.

'PART OF BROADER PLAN'

Tensions have mounted on NATO's eastern flank with Russia in recent weeks. Apart from the Polish incursion, Estonia accused Russia of sending three fighter jets into its airspace last week, while Romania has come close to shooting down a drone.

Earlier on Friday, the Kremlin said that talk of shooting down Russian military planes over Europe was reckless, aggressive and marked a serious escalation of tension near Russia's border.

Without addressing the more recent incidents, the Ukrainian agency said: "This incident (in Poland) is part of Russia's broader plan to expand aggression into countries bordering Ukraine".

"It serves as a warning to NATO and a test of their response to attacks on member states. It is also intended to intimidate the Polish population."

It assessed there had been 10 violations of Moldovan airspace by Russian drones this year, and that 14 drones had crashed on Romanian territory during attacks on nearby port infrastructure in Ukraine since 2023.

"Violations of airspace in countries bordering Ukraine have become systematic during Russian combined air attacks on Ukrainian civilian and critical infrastructure," it said.

(Reporting by Tom Balmforth; Editing by Howard Goller)