ENThis article is part of a broad discussion concerning the deteriorating security environment in the European neighbourhood and the initiatives the European Union (EU) and its Member States (MS) took to intensify security and defence cooperation. The war in Ukraine put pressure on the entire regional security structure. Hence increased investments and more collaboration are necessary to jointly develop and use the military capabilities that the EU and Baltic region need. In this context, it is interesting how Lithuania and Poland – both Eastern EU members with grave concerns and engagement in regional security – perceive and utilize the potential that EU programs offer. This article will look deeper into the level of cooperation between Lithuania and Poland before the intensification of military operations in Ukraine in February 2022. Furthermore, the paper presents an overview of the regional cooperation concept, Common Security and Defence Policy (CSDP), and its funds, agencies, and instruments. The key elements of this study are the analysis of both countries’ involvement in the European Defence Fund (EDF) preparatory programs implemented since 2017. Keywords EDF, PESCO, CSDP, military cooperation, regional cooperation, European funds, EDIDP, PADR. [From the publication]