Vladimir Putin’s invasion of Ukraine has transformed Europe within a matter of weeks. A continent once fractured by the refugee crisis is now taking in millions of refugees. Countries such as Germany have made considerable pledges to increase military spending. The European Union said it would cut off Russian oil and gas “well before 2030” — a once unthinkable prospect. The European project seems more confident in itself than at any other time in recent history.But some European countries are also seeing trends in the opposite direction. This month in Hungary, Prime Minister Viktor Orban’s nationalist government won re-election easily. The far-right leader Marine Le Pen lost this past weekend’s French presidential election to the incumbent, Emmanuel Macron, but secured a significant 41.5 percent of the vote, up from 33.9 percent in 2017. And nationalist movements — Brexit in Britain, the Five Star Movement in Italy and others — have become potent political forces in recent years.So what’s next for Europe? Will Putin’s invasion reinvigorate the collective European project? Or will the continent revert to its preinvasion path of fracture, division and nationalism?Ivan Krastev is the chairman of the Center for Liberal Strategies in Sofia, Bulgaria and the author of numerous books, including “After Europe” and, with Stephen Holmes, “The Light That Failed: Why the West Is Losing the Fight for Democracy.” He’s also one of my favorite people to talk to on the subject of Europe, liberalism, democracy and the tensions therein.We discuss how European identity went from revolving around war to being centered on economic trade, why Europe has treated the Ukrainian refugee crisis so differently from previous refugee crises, how the West’s overly economic understanding of human motivation blinded it to Putin’s plans, what the relative success of politicians like Le Pen and Orban means for the future of Europe, how fears of demographic change can help explain phenomena as different as Putin’s invasion and Donald Trump’s election, whether Putin’s invasion can reawaken an exhausted European liberalism and much more.Mentioned:“The End of History?” by Francis FukuyamaThe End of History and the Last Man by Francis Fukuyama“We Are All Living in Vladimir Putin’s World Now” by Ivan Krastev“The Crisis of American Power: How Europeans See Biden’s America” by Ivan Krastev“The Power of the Past: How Nostalgia Shapes European Public Opinion” by Catherine E. de Vries and Isabell Hoffmann from Bertelsmann StiftungBook Recommendations:Free by Lea YpiThe Age of Unpeace by Mark LeonardTime Shelter by Georgi GospodinovThoughts? Guest suggestions? Email us at ezrakleinshow@nytimes.com.You can find transcripts (posted midday) and more episodes of “The Ezra Klein Show” at nytimes.com/ezra-klein-podcast, and you can find Ezra on Twitter @ezraklein. Book recommendations from all our guests are listed at https://www.nytimes.com/article/ezra-klein-show-book-recs.“The Ezra Klein Show” is produced by Annie Galvin, Jeff Geld and Rogé Karma; fact-checking by Michelle Harris; original music by Isaac Jones; mixing by Jeff Geld; audience strategy by Shannon Busta. Our executive producer is Irene Noguchi. Special thanks to Kristin Lin and Kristina Samulewski.