It comes down to blood. Which side can bleed more. And the answer is Russia. Someone can correct me on this story, but it goes like this… A country goes to war agains China. Every day the Chinese lose one million fighters. After 100 days the enemy surrenders to China. Suffering and dying is part of the Russian psyche. They will bleed their own country dry and consider it a patriotic gesture.
They actually still believe they are dying in droves, just naruto running into the bullets in human wave attacks.