If you look at the AOPS, I think the answer is in what it can do. It cannot operate in the Arctic throughout the entire year. I think that answers your question right there. What happens if a threat surfaces or develops at some time when they're not available? The short answer is that they don't meet the need.
Secondly, on whether they are armed enough, I'm not in the navy, but the short answer is no, in my opinion.