Russia’s aggression against Ukraine in 2014 and 2022 changed the security environment and prompted Sweden to renew its focus on national defence, leading to accession to NATO in 2024. Several studies have explored soldiers’ motivation to serve during an era marked by international military operations following the Cold War. However, no study has to date examined soldiers’ motivation within the context of Sweden’s reformed defence policy. This qualitative interview study aims to explore how enlisted soldiers in the Swedish Army experience their motivation to serve in this evolving context. Using thematic analysis for data analysis and Battistelli’s model of motivation as a theoretical lens, the results from this semi-structured interview study highlights patriotism, altruism, collegial loyalty, and a desire for professional development as key motivational factors. NATO membership is perceived as both reinforcing and challenging — enhancing purpose for some while generating ambivalence in others, considering the shifting defence posture.