A Mil Mi-8 Russian Border Guard helicopter entered Estonian airspace without permission on Saturday night (June 18), the Ministry of Defense said.
The aircraft flew above the Koidula region of south-eastern Estonia, which borders Russia, for approximately 2 minutes, the ministry said in a statement issued on Tuesday.
A flight plan was not filed, the transponder was switched off and two-way radio communication was not established with Estonian air traffic control.
Russia's Ambassador to Estonia Vladimir Lipaev was summoned by the Estonian Ministry of Foreign Affairs and handed a note on Saturday.
"Estonia considers this an extremely serious and regrettable incident that undoubtedly causes additional tensions and is completely unacceptable," the MFA said in a statement released on Tuesday.
This is the second time in 2022 that Russian aircraft have breached Estonia's airspace. Last year, there were five such incidents.
While this is a rare event in Estonia, Lithuania's Ministry of Defense reports that Russian warplanes fly through the country's airspace every week, usually without prefiled flight plans and switched off transponders. Last week there were eight violations and 13 the week before.
Last month, Russia also briefly flew a helicopter in Finnish airspace.
Editor's note: This article was corrected to clarify the helicopter belonged to the Russian border guard.
Editor: Helen Wright