Yes. I'll comment, if I may, in two ways.
First, I would say, in specific answer to your question about a doctrine, there is policy work under way right now, the Arctic policy framework. Of course, that builds on the oceans protection plan that builds on the defence policy review. Of course, I can't speak to what the Arctic policy framework will end up looking like, but issues around security and defence are certainly part of the work that is under way now.
I would at the same time just go back to my introductory comments in recognizing that Russia is modernizing its military after a period of considerable shrinkage. I had a conversation with a think tank some months ago that referred to Russia's inability to know what's going on at their own northern coast as part of their rationale. That's not to say it isn't something on which we should be vigilant. Of course we should, but we recognize as well that Russia does have these economic interests it wants to protect. Part of protecting those economic interests is ensuring that, in their rhetoric but we all agree on it, the Arctic should remain a zone of peace and co-operation. For them to threaten our space undermines what they're trying to do in their own Arctic in protecting those economic interests.
That's not to say that is a reason to be complacent. I need to reiterate that vigilance is key, but it is part of the geopolitical analysis.