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 military aircraft fly close to the country's airspace every week, usually without pre-filed 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