Russia is preparing for a military confrontation with the West within the next decade and could be deterred by a counter build-up of armed forces, Estonia's Foreign Intelligence Service said on Tuesday, Paralel.Az reports citing Reuters.

A growing number of Western officials have warned of a military threat from Russia to countries along the eastern flank of NATO, calling for Europe to get prepared by rearming.

The chief of the intelligence service said the assessment was based on Russian plans to double the number of forces stationed along its border with NATO members Finland and the Baltic States of Estonia, Lithuania and Latvia.

"Russia has chosen a path which is a long-term confrontation ... and the Kremlin is probably anticipating a possible conflict with NATO within the next decade or so," Kaupo Rosin told reporters at the release of Estonia's national security threats report.

A military attack by Russia is "highly unlikely" in the short term, he said, partly because Russia has to keep troops in Ukraine, and would remain unlikely if Russian buildup of forces was matched in Europe.

"If we are not prepared, the likelihood (of a military Russian attack) would be much higher than without any preparation," Rosin added.

Estonia and the other Baltic States have increased their military spending to over 2% of the value of their economies after Russia annexed Crimea in 2014, and NATO allies have raised their presence in those countries.

Germany plans to have 4,800 combat-ready troops in the region by 2027, in its first permanent foreign deployment since World War Two, and Rosin said NATO and its allies were moving in the right direction to counter the Russian threat.

Rosin does not expect a Russian breakthrough in Ukraine before its presidential election in March, as it would need to mobilise significantly more troops to achieve that goal.

Speaking about U.S. presidential candidate Donald Trump's comments that he would not defend allies who don't spend enough on defence, Rosin said: "Such statements are never helpful".

Russia's ability to provide ammunition to its troops is continuing to outweigh Ukraine's, and unless Western support is sustained or increased, Ukraine is unlikely to be able to change the situation on the battlefield, he added.