This article addresses the research problem of analysing the development of the EU Common Security and Defence Policy (CSDP) in the context of the ongoing war in Ukraine. It examines the extent to which Russia’s military actions against Ukraine, particularly those starting in 2022, have influenced EU and Member State decisions regarding the CSDP. To provide a more comprehensive analysis, this study also explores the evolution of the CSDP, focusing on its foundations and conditions both prior to the full-scale conflict and following Russia’s 2014 aggression in Crimea and Donbas. This broader perspective enables a thorough assessment of the scale and scope of CSDP reforms over time. The objective of this article is to examine the dependencies and impacts of the war in Ukraine on the development and evolution of the CSDP.