Across Europe, a quiet war is being waged in the margins of attribution — in burned warehouses, intercepted drones, and severed cables that no one can definitively trace to Moscow. NATO's deputy commander, speaking in Estonia this week, placed this accumulation of ambiguous harm within a larger strategic logic: Vladimir Putin, under mounting pressure from a costly and stalled war in Ukraine, is probing the edges of Western resolve without crossing the threshold that would demand a unified response. The pattern raises an ancient question about collective security — at what point does the sum of