Estonia's Foreign Intelligence Service said it believed Russia still had the strength to exert "credible military pressure" on the Baltic region, where the security risk has risen for the medium and long-term.
NATO and the European Union members Estonia, Latvia and Lithuania - the so-called Baltic states - have sharply boosted defence spending in response to Russia's 2014 capture of Crimea from Ukraine and the invasion of Ukraine last year.
"A military attack against Estonia is unlikely in 2023" due to Russia's invasion of Ukraine, but "in the mid-to-long term, Russia's belligerence and foreign policy ambitions have significantly increased the security risks for Estonia," the Estonian service said in its annual report on Wednesday.
"Russia considers the Baltic states to be the most vulnerable part of NATO, which would make them a focus of military pressure in the event of a NATO-Russia conflict."
Russia's military presence near the Baltic states' borders could be rebuilt in four years, the intelligence service said.
Russia's plan to conduct large-scale military exercises at its western borders two years earlier than scheduled could further strain the security situation in the Baltic region this year, it said.
Moving forward the major exercise - to some time this year - at a time when Russia has invaded Ukraine, "can be seen as a deterrent and threat to the West and as an incitement to patriotism among the Russian population", it added.
The Estonian intelligence service said Russia remained determined to continue its invasion of Ukraine through 2023, as it attempts to wear down Kyiv and its western backers into submission, but was "unlikely" to use tactical nuclear weapons in the conflict.
It said President Vladimir Putin's government was certain to remain in power for the foreseeable future, and that any replacement would be unlikely to be democratic.
(Reporting by Andrius Sytas in Vilnius, editing by Terje Solsvik and Bernadette Baum)
