much of this land was part of Russia before and many Russian people live there.
See Troll Bingo above.
By the same token, I look forward to Putin handing back Kalingrad to Germany and the Kuril Islands to Japan, and respecting Siberian calls for independence
Russia bans Siberia independence march | World news | theguardian.com
Besides the Russians have only used a limited number of forces and may withdraw them after the troubles are over.
From Crimea (you know, that part of Ukraine that Russia invaded and annexed)? Of course not - see Troll Bingo for 'Crimea was a special case'.