alt Hacker NewsSvalbard is another possible obvious target. It has a Russian population, is quite some distance from the mainland, and is essentially undefended.
It would be easy to set up a Russian military presence, and it would be hard to dislodge it from a distance without considerable effort and expense.
This doesn't seem that useful? Svalbard would require significant, continued supply. Unless the Russian navy is able to own the Barrents Sea, any force on Svalbard could just be waited out. Once the diesel is out, the defenses go down and they freeze. Not to mention that it is well in range for medium range ballistic misses from Greenland, Iceland and the Nordics.