Two Ukrainians were arrested in Poland - they are suspected of espionage and arson.
Young men aged 24 and 25 were in custody.
They are alleged to have photographed military installations and critical infrastructure, as well as set fire to cars, after changing their license plates to match those of Ukrainian military vehicles in order to stir up anti-Ukrainian sentiment.
In the investigation it was claimed that the Ukrainians acted according to the instructions of the Russian special services.