As the war in Ukraine enters its fourth year, NATO's senior commanders have arrived at a quiet but consequential conclusion: Vladimir Putin is becoming more comfortable with risk, more willing to test the boundaries that have long kept European conflict contained. The alliance is no longer planning only for Ukraine — it is preparing for what might come alongside it or after it, from the grey-zone provocations already underway across the continent to the possibility of a limited incursion into Estonia's border city of Narva. This is the long work of deterrence in an era when the old calculation