Poland said on Monday that its planes had intercepted a Russian reconnaissance plane over the Baltic Sea, Reuters reported, quoted by BTA.
This is the third such incident this week.
The plane did not violate Polish airspace, the Polish Armed Forces' Operational Command said, but as in previous incidents, it had not declared a flight plan and its transponders were turned off.
"This is already the third such situation this week, which confirms the increasing activity of Russian aviation in the Baltic region," the army stressed.
NATO's eastern flank has been on heightened alert for potential airspace violations since September, when three Russian military aircraft violated Estonian airspace for 12 minutes, just days after more than 20 Russian drones entered Polish airspace.