Because it's a bad idea to do so. If Russia were to commit true genocide -- kill 40 million people in Ukraine by levelling the country -- it would serve no mili

Because it's a bad idea to do so. If Russia were to commit true genocide -- kill 40 million people in Ukraine by levelling the country -- it would serve no military purpose. On the other hand: - Putin would go down in history as worse than Hitler - Thousands of people -- including, for example, Russians with relatives in Ukraine -- would want to kill Putin. Russia would have a terrorist and fifth column problem unprecedented in the history of the world. - Russia would go from "outcast" to "North Korea level outcast." China and India would almost certainly turn against it - It just might be far enough to draw NATO / EU into the war. That's a war Russia is guaranteed to lose. If nukes fly, everyone loses. If they don't, Russia loses. ... and so on. How would it advance Russia's interests? The above far outweighs the benefits (oil, Crimea, and a bit of a buffer zone).