Full scale is unlikely. Russia could not, but they might send 250k/year to die in Estonia. EU and Nato (with or without US) would defend. But I doubt they would go all the way through Russia to force them to stop.
Nuclear option is not likely to be used for some "minor" conflict like that, because it would go both ways quickly.
Nuclear option is not likely to be used for some "minor" conflict like that, because it would go both ways quickly.