This study explores the evolution of rhetorical strategies in Swedish parliamentary debates concerning NATO membership from 2015 to 2024, with emphasis on the impact of Russia’s 2022 invasion of Ukraine. Drawing on classical rhetorical concepts (ethos, pathos, logos) alongside contemporary framing theory, this analysis focuses on how political leaders articulate positions, establish credibility, and reshape perceptions of national security. The results reveal a marked rhetorical shift post-2022, wherein NATO is increasingly portrayed as a pragmatic and essential safeguard in an unstable geopolitical climate. Prior emphasis on military non-alignment and independence gave way to discourses stressing collective responsibility and strategic alignment. This study underscores the role of language as a key mechanism in legitimizing policy changes and influencing public attitudes, as well as the importance of rhetorical analysis in political science by showing how discourse actively shapes political reality and helps explain policy shifts during international crises.