It's been more than 60 years since the founding of NATO. While I'm inclined to agree that Russia is a threat of a kind to eastern Europe, it is a threat of a different kind than it has been for most of the last 60 years.
Is Russia liable to send troops into eastern Europe tomorrow? Very unlikely. Is it possible it might do so 10 years from now? Possibly. But fundamentally, surely this is a European problem.
Canada has an interest, but it is somewhat less of an interest, I would suggest, than what we had 60 years ago when it was a worldwide Cold War taking shape. I don't see the Russians being likely to take that kind of approach on a global scale in the near future.