No one is going under multi year ice in the Canadian NWP. Perhaps north of Elsmere. I think you underestimate the challenges of ice even for submarines. Particularly when the ice dams can reach all the way to the bottom of the ocean, and the iceburgs regularly scrap along.
Perhaps there is some bunker busting ordinance that can penetrate through ice and release a torp. That would be interesting... Maybe something for BOREALIS to work on! lol
Its the first step, and letting them do stuff without knowing that we know they are there, isn't the worst idea.
No need for the nuclear ship, but the Polar class' being built at Davie and Seaspan will be enough for now. Not that they are going to be able to see subsea either. You can't do that with an iicebreaker overly well. Maybe release some things via the moonpool (UUV's).