PARIS — The war in Ukraine is driving a shift toward fast-changing, mass warfare that Western militaries are unprepared for, while Russia is adapting rapidly, according to Adm. Pierre Vandier , NATO’s Supreme Allied Commander Transformation. The gap between what Europe should be doing for defense and its actual capabilities undermines deterrence, risking Russian aggression if Moscow concludes Europe or NATO are too weak to resist attack, Vandier said at the Paris Defense & Strategy Forum on