“Putin was very clear, as were all his lieutenants, that their great fear was that Ukraine was becoming a Western bulwark on Russia's borders. For them, that was an existential threat. It was simply unacceptable.”

American political scientist and international relations scholar

John Joseph Mearsheimer is an American political scientist and scholar of international relations, and a professor at the University of Chicago. He is known for his work on great power politics and the theory of offensive realism. His writing and teaching focus on how states compete for power in an anarchic international system. He has become widely associated with realist thinking in international affairs, especially questions of security, rivalry, and the behavior of major powers.