On Finland side, there's a safety zone a few km wide, preceding the Russian border. It's forbidden to enter this zone without permit, and you would be well advised to obey the ban. This zone is tightly monitored with cameras and other equipment, and the border guards patrol it regularly.
You'll see plenty of these signs, and yellow tape attached to the trees indicating the edge of the zone. Perhaps half of the time on this route, the roads follow the edge of the border zone.