Russia’s full-blown invasion of Ukraine has reaffirmed Nato as the cornerstone of Europe’s defence and forced leaders of the security alliance to rethink how they face down Moscow in a return to cold war doctrine.

Four announcements — a goal of a sevenfold increase in Nato forces on high alert, the first permanent US base on the alliance’s eastern flank, an invitation to Finland and Sweden to join and a new 10-year guiding strategy that ditches any illusion of partnership with Moscow — amount to a fundamental sharpening of focus for the alliance.

“We will enhance our collective defence exercises to be prepared for high-intensity and multi-domain operations and ensure reinforcement of any ally on short notice,” Nato leaders said in a joint declaration. “This will help to prevent any aggression against Nato territory by denying any potential adversary success in meeting its objectives.”