In this episode, Matthew Evangelista discusses his recent International Security article, “A ‘Nuclear Umbrella’ for Ukraine? Precedents and Possibilities for Postwar European Security.” How can Ukraine and Europe deter further Russian aggression after the Russo-Ukrainian war ends? The conventional wisdom holds that Ukraine should join NATO to shelter under the U.S. nuclear umbrella. Evangelista challenges this assertion, arguing that nuclear deterrence was never tested during the Cold War. He proposes an alternative way to reestablish European security: a non-offensive, confidence-building defense that does not rely on the threat of nuclear war.