"As by nature and scenario Zapad has been about attack rather than defense tasks, NATO must also take Russia's plans seriously," Mihkelson told BNS on Friday. "Russia is the only country that is teaching its military muscle the habit of holding a large conventional war against Western countries. A vivid confirmation of that was the series of exercises that took place this year and culminated with Zapad."

The German magazine Der Spiegel reported that Russia wants to considerably expand the large military exercise Zapad in the immediate vicinity of NATO's eastern border. Instead of every four years, the exercise involving all arms of the service with up to 100,000 defense personnel, hundreds of tanks and military aircraft is to be held every two years in cooperation with Belarus.

"NATO and EU member states should draw serious conclusions from this and continue developing the deterrence measures agreed upon already at the NATO summit in Warsaw," Mihkelson said, referring to the summit which took place in July 2016.

"For Estonia, it is especially important here to develop anti-aircraft capability and more visible activity of NATO member states on the Baltic Sea," he continued. "Only deterrence measures are a guarantee that a rule-based substantive dialogue could be restored in the relations between Western states and Russia.

"In the past few years especially, Russia has lived in the steady rhythm of military exercises, which is why it is not surprising if Zapad will be held more often than before," Mihkelson said. "It must be taken into consideration that Russia has visibly invested in the Western direction, from the Arctic to the Black Sea, both in A2/AD air defense or essentially establishing no-fly zones and creating large units capable of fighting." He cited as an example the large units of the 1st Guards Tank Army and three new divisions on the borders of Ukraine. "This is why it is natural that practicing these forces together requires a closer and at the same time large-scale training plan."

Previously, the joint military exercise was held every four years, and exercises were held in Russia's Eastern, Southern and Northern military districts during other years.

According to a NATO analysis, the exercise held in cooperation with Belarus this September was only the core of a much larger maneuver. NATO said that the large-scale exercises connected with Zapad were held from the border between Ukraine and Russia in the south to the Kola Peninsula up to 2,000 kilometers north.

According to the alliance's analysis, Russia proved with the recent exercise that it is capable of operating simultaneously with all arms of its military — including the army, air force and navy — across the whole of NATO's eastern border. Issues with service command were still detected during the previous Zapad exercise in 2013.