Abstract
This study aims to analyse the evolution of the relationship between the European Union (EU) and the North Atlantic Treaty Organisation (NATO) in the recent decades, particularly with the implementation of the EU's Common Security and defence Policy (CSDP). This study also aims to improve knowledge of the trends of different approaches in the EU about this relationship. Strengthening the cooperation in the field of security and defence is vital for the EU, considering the implications of the Russian invasion of Ukraine and the current hostile international environment, with increasing geopolitical competition between the great powers.