‘Crossing the Rubicon’: Explaining Sweden’s decision to join NATO

In May 2022, Sweden took the historic decision to apply for NATO membership, thereby ending two-hundred years of neutrality and military non-alignment. How can we explain such a dramatic change in Swedish foreign policy? Although Russia’s invasion of Ukraine constitutes a critical juncture for Sweden and Europe, Swedish neutrality and non-alignment has survived other eruptions of major interstate war in Europe. In this article, we argue the Swedish decision to join NATO represented the ‘tipping point’ of a long and incremental process of change in Swedish security policy. Our analysis utilises a neoclassical realist framework which focuses on examining interlinkages between systemic change and unit-level factors. We conclude that in the case of Sweden, exogenous systemic pressures created a critical juncture, but policy change was only possible because of far-reaching transformations of Swedish foreign policy role conceptions and strategic culture, along with the critical role played by policy entrepreneurs in crisis decision-making.