Russia’s full-scale invasion of Ukraine in February 2022 is reshaping the security environment in Europe and has ramifications elsewhere. The scale of Moscow’s miscalculation is apparent nearly a year on, but at the outset it was not clear that Russia would face such difficulty. One of the preliminary lessons offered by the war – beyond those for the belligerents – is that defence and intelligence specialists need to sharpen focus on methodologies important to the assessment of military capabilities, and in this case revise how they evaluate Russia’s armed forces. Other early take-aways include those related to the importance of aspects of military capability such as intelligence, surveillance and reconnaissance (ISR), longer range artillery and better targeting, and the importance of training and morale. Yet more concern resilience, both civil and military. Meanwhile, although the United States has led international military support for Ukraine, and Washington perceives Russia as the immediate threat, its longer-term focus remains what it views as the challenge from China. Beijing continues to modernise its armed forces at pace. Russia’s war also offers lessons for the US armed forces and its defence industry, both for its involvement in Europe, but also in possible contingencies elsewhere, including in Asia.