The war started by Russia in Ukraine has caused a lot of challenges for economic development. It is hardly imagined without the contribution of research and innovation. Rebuilding R&I became another challenge for Ukrainian policymakers. Thus, the purpose of the paper is to analyse the R&I policy of Ukraine during the war caused by Russia and to develop policy recommendations for the post-war recovery. To achieve it, we used several methods, in particular expert opinion generalization, relevant scientific and policy literature analysis, and statistical analysis. The paper considers three approaches to innovation policy, that Ukraine could choose as a response to the war: produce; buy; repurpose. Currently, Ukraine uses mainly the second one, by buying and receiving modern armament and equipment. Meanwhile, there were some innovative developments in Ukraine, which are not produced in sufficient quantities. After the war, Ukraine couldn’t buy armament due to fiscal constraints. Thus, in the short-run period, the government should reorient efforts using repurpose approach. However, such an approach is not sustainable in the long-run period, when the development of a broader S&T base is required to create a solid base for further repurposing in emergency cases. The war caused massive damage to Ukrainian R&I potential, which by now is not fully measured and quantified. There are two types of damage: physical loss of research and innovation infrastructure (e.g. research facilities, and high-tech enterprises) and «brain drain», which should be at the focus of R&I policymakers. Therefore, a set of policy measures is proposed to address the war-led challenges in R&I.