If tiny Norway, which imposes no real threat to any other country, including it's mighty neighbor, Russia, is a target for intelligence services, then every country is a target.
Norway has little strategic importance and little influence on the world economy or world peace. Sure, they have lots of oil but its undisputed Norwegian and they sell it willingly. Sure, they are NATO members and at present the NATO secretary general is Norwegian, and they do participate in NATO actions in the Middle East. But their own military is modest, barely capable of defending Norway if it came down to it. And Norway has little say over the other NATO countries.
I think the NATO secretary general, Stoltenberg, said it best himself when he described the Norwegian democracy as a fax democracy where Norwegian officials sit at a fax machine waiting for the latest directive from Brussels (Norway is not an EU member but part of the European Economic Area and must adopt most EU rules in order to keep their access to the Euroean single market).
Anyone thinking that Norway has any real powers or impose a threat to anyone in the next 5-10 decades is delusional.
So why and to whom is it vital to spy on these fax politicians whose international influence barely exceeds that of an American senator or governor or a member of a German Landtag?