A "serious threat to peace" – that's how Poland sees Russia's largest drone incursion into its air space so far. German Chancellor Merz agrees. But what will NATO, what will the EU do in response? "Russia is testing Europe" DW Eastern Europe Correspondent Roman Goncharenko tells Berlin Briefing's host, Michaela Küfner. Pulling together the analysis from Berlin and Brussels DW's political quartet including Chief Political Correspondent Nina Haase and Brussels Correspondent Teri Schultz explore