The Estonian Foreign Ministry said three Russian MiG-31 fighter jets had entered Estonian airspace in the Gulf of Finland and stayed there for 12 minutes.
Italy's F-35 fighter jets deployed in Estonia as part of NATO's Eastern sentry campaign, along with those from Sweden and Finland, responded to the encroachment, according to the headquarters of the NATO Allied Campaign Command.
Estonian Prime Minister Krisen Michal said the Russian aircraft were later forced to leave. Meanwhile, NATO Secretary General Mark Rutte praised the alliance's "quick and decisive" response.
For its part, Russia denied that the plane violated Estonian airspace, asserting that the flight " Strictly followed international rules" and "not violated the borders of other countries".
The Russian Defense Ministry stressed that the country's aircraft flew over the "neutral waters of the Baltic Sea" en route from Karelia - a northwestern Republic of Russia - to an airport in the Kaliningrad region - Russia's overseas territory between Poland and Lithuania, and more than 3km north of the northernmost point of Estonia.
The Estonian prime minister said that Estonia had requested consultations under NATO Article 4 after the above-mentioned "completely unacceptable" violation. A NATO spokesperson allison Hart said NATO will meet early next week to discuss the incident in more detail.
Article 4 of the NATO treaty stipulates that any member country can officially submit the issue to the council - the main decision-making agency of the alliance - to meet and discuss the next steps when the territorial integrity, political independence or security of the member country are threatened.
Poland has launched a similar consultation after several drones and fighter jets believed to be Russian flown into the country's airspace last week.
The Estonian Foreign Ministry has summoned Russia's interim prosecutor for the incident.
A few hours later, Polish border guards reported that two Russian fighter jets had "flyed low ground" over an oil rig in the Baltic Sea owned by Polish oil and gas company Petrobaltic.
