How would Estonia and its NATO allies respond should the small Baltic state be invaded by Russia?

Estonia: Going on a Bear Hunt

Russia says that no more than 12,700 of its troops will be participating in what are purely defensive exercises; NATO officials say the real number of Russian military personnel involved could reach 100,000 and are part of a muscular display of firepower aimed at unsettling some of the more vulnerable members of the Western alliance.

It's a grumbling dispute over war games being staged along Russia's northwestern borders this September, that hasn't yet become a full-blown quarrel, but can perhaps be seen as a sign of the times.

... the Russian 2017 war games are taking place after three years of mounting tension along its borders with Europe, in the still-turbulent backwash of its 2014 annexation of Ukraine's Crimean Peninsula and when relations with the West, over everything from Russia's military support for Syria's Bashar al-Assad to perceived interference in the US presidential elections, have become increasingly tetchy.

Read more at:
http://www.aljazeera.com/programmes/peopleandpower/2017/09/estonia-bear-hunt-170914055839448.html