NATO member Estonia's airspace was violated by three Russian military jets on Friday, its government said, amid an increasingly tense atmosphere on the alliance's eastern flank.
The incident comes just over a week after more than 20 Russian drones entered Polish airspace on the night of September 9-10, prompting NATO jets to down some of them and Western officials to say Russia was testing the alliance's readiness and resolve.
Tallinn said on Friday the three MiG-31 fighter jets entered Estonian airspace without permission and stayed there for a total of 12 minutes.
"Russia has violated Estonian airspace four times already this year, which is unacceptable in itself, but today's violation, during which three fighter jets entered our airspace, is unprecedentedly brazen," said Foreign Minister Margus Tsahkna.
"Russia's ever-increasing testing of borders and aggressiveness must be responded to by rapidly strengthening political and economic pressure."
Estonia said it had made a protest to the top Russian diplomat in the country.
A staunch supporter of Ukraine, Tallinn said in May that Moscow had briefly sent a fighter jet into NATO airspace over the Baltic Sea during an attempt to stop a Russian-bound oil tanker thought to be part of a "shadow fleet" defying Western sanctions on Moscow.
