John is right! : A Process Tracing Study of NATO Expansion and the 2022 Russian Invasion of Ukraine

This thesis investigates whether NATO’s post–Cold War expansion was the root cause of Russia’s full-scale invasion of Ukraine in 2022. Relying on the theoretical framework of John Mearsheimer’s offensive realism, the study employs process tracing to reconstruct a causal sequence linking NATO enlargement to Russia’s decision to launch the war. The analysis is grounded in officially published, open-access sources such as summit communiqués, diplomatic statements, and public speeches, allowing for transparent and verifiable empirical reconstruction. The central hypothesis posits that the strategic logic of NATO expansion —particularly the 2008 promise of eventual membership to Ukraine — triggered a predictable series of reactions by Russia, culminating in war. The alternative explanations rooted in ideology, domestic politics, or personal motivations are treated as competing hypotheses. The findings indicate that Russia’s actions followed a rational security logic consistent with the expectations of offensive realism. The thesis does not seek to justify aggression but aims to understand the structural conditions that made the war likely. By testing theory against historical events, this work contributes to the broader discussion on great power politics, NATO–Russia relations, and the role of structural forces in the onset of major conflicts.