Kharkiv Region, Ukraine: The motivation to keep fighting the Russians is simple for Viking, a Ukrainian soldier near the northeastern frontlines as cold weather and artillery onslaughts bogs down both sides. He wants revenge.“I can say that the hardest thing for me is the death of my friends. I had motivation before... but the anger, aggression and hatred reinforces it,” says Viking, the nom de guerre of the 26-year-old tank gunner.But despite the heavy losses incurred by the Ukrainian...