Latvia’s National Armed Forces (NBS) reported that at least one drone had entered the country’s airspace — the third consecutive day such an incident has occurred.

The Latvian military reported a possible airspace threat around 11 a.m. in the Ludza, Kraslava, Rezekne, and Augsdaugava districts, which border Russia and Belarus. Local authorities in the Kraslava district confirmed to the Leta news agency that a drone had been spotted flying over the area.

Train service in the Ludza, Rezekne, and Kraslava districts has been suspended, the Baltic news website Delfi reported, citing Latvian railway operator AS Pasažieru vilciens.

In recent months, drones have been increasingly straying into the airspace of Northern European countries. According to one theory, Russia’s armed forces are using electronic warfare to alter the flight paths of Ukrainian drones so they fly toward European countries that border Russia.

After two Ukrainian drones entered Latvian airspace from the direction of Russia in early May, Latvia experienced a political crisis. Against the backdrop of the incident, the ruling coalition effectively collapsed and the government resigned.