Capetonian, I would say the greatest threat to world peace would be the US government blundering around the world from one disaster to another. (Just look at Iraq and Libya right now)
I think in this day and age the idea of Russia invading Finland or Sweden is very unlikely. If they are worried simply keep and maintain a strong independent military of their own. Putin really is not so bad, he was forced into the actions he took in Ukraine by the western back coup. What exactly did western leaders expect him to do. He also managed to prevent a western backed war in Syria that would have helped Isis and other terrorists.