This study analyses the controversy and decidedly mixed views surrounding the EU defence collaboration in the 21 st Century. It investigates on the 21 st Century challenges faced by the EU in its defence collaboration and its implications on interventionism. The EU defence collaboration was initially developed by historically fractious Western European states in the late 1940s as a response to growing threats posed by the Soviet Union. The EU defence collaboration through-out the 90s showed some commendable level of unity which has since taken a paradigm shift in the 21 st Century. Thus, the EU defence collaboration is deteriorating and needs to be revitalized before the situation goes out of hand. Primary data analysis was used to solicit relevant data and thematic analysis was used to analyse data obtained. The findings showed that, there is lack of unity of purpose among member states in carrying out their defence mandates, lack of commitment by member states to meet their financial obligations requisite for effective and efficient defence collaboration and lack of trust among member states as the major limitations to the effective defence collaboration as member states are skeptical of each other's intentions. Hence, after a critical analysis of the data analysed, this research proposes that the EU should adopt sterner measures to ensure that member states meets their financial obligations and that the EU should be consistent in its policies in order to fulfil its mandates and obligations.