<p>Russia’s second invasion of Ukraine beginning in February 2022 was a major political shock to Europe. Or was it? Certainly, European perceptions toward Russia, the alliance’s deterrent posture, and defense spending changed fundamentally. The long-standing two-pronged approach toward Russia—defense and dialog—appears gone, replaced by a set of economic sanctions, diplomatic distancing, and strategic reappraisal. The alliance appears well on the way to fully embracing collective defense and preparations for larger-scale maneuver warfare. However, the alliance response to Russia’s war remains a work in progress, including in terms NATO’s command structure, force structure, readiness, and posture and even its relationship with Russia. Among the allies, the degree of policy change remains somewhat uneven, with some members instituting dramatic shifts and others less so. The academic literature on political shocks can help to frame the differentiation among allies as well as the evolving nature of NATO’s response.</p>