sentences:  Regardless of these factors, Estonia has responded to Russia with frequent large-scale national and volunteer military exercises along the Russia-Estonia border.Additionally, Estonian government officials have called upon NATO, who has pledged their support for Estonia in the effect of Russian encroachment, by sending individuals to take place in the military exercises along the border.According to Levada Center Russian research institute, in 2007, Estonia was considered an enemy of Russia by 60 percent of Russia's citizens (cf.