This week Mark Leonard welcomes Piotr Buras senior policy fellow and head of ECFR’s Warsaw office to discuss the recent shifts in Europe’s defence strategy. On the weekend, Germany’s chancellor-in-waiting Friedrich Merz’s has said he would pursue discussions with France and Britain on sharing nuclear weapons. Meanwhile, Polish prime minister Donald Tusk is looking into the possibility of nuclear deterrence and has proposed compulsory military training for men. Are we witnessing a fundamental shift in Europe’s security posture? How do Tusk’s remarks tie into Merz’s comments? Are we seeing the end of America’s nuclear umbrella in Europe, or at least the end of its credibility?