NATO and EU officials say allies are investing faster, with a growing number meeting the alliance’s spending guidelines as Europe boosts air defenses, stockpiles and military production. The war has also exposed vulnerabilities beyond the front line, including to cyberattacks, disinformation and pressure tactics targeting energy and infrastructure. Analysts say the conflict is forcing Europe to confront a strategic question it long avoided: how much it can rely on US support. For many capitals, the post–Cold War era is over and planning for a different kind of war has begun.