From crisis to cohesion: the impact of the 2022 Russian invasion of Ukraine on European Union identity

Social identity theory suggests that an external threat, such as the Russian invasion of Ukraine, can increase in-group identification and foster a shared sense of identity. While previous research has shown that the shock of Russian aggression positively influenced support for the EU among European citizens, we lack a comprehensive understanding of how individual differences in threat perceptions relate to identification with the EU. Drawing on survey data from 16 countries collected just five weeks after the 2022 invasion, we demonstrate that the "rally around the European flag effect" is most pronounced among those who perceive Russia as the greatest security threat to their country. By utilizing machine learning techniques and a generalized random forest, we further reveal the heterogeneity of this effect. Perceiving Russia as a threat is most strongly linked to an increase in European identification among individuals with an exclusive national identity -- i.e., among those who are otherwise unlikely to express a sense of pride in being part of the EU. By emphasizing that even those with a primarily national identity can be swayed to feel attached to the EU in times of crisis, our study contributes to the growing body of literature that investigates the psychological foundations of support for the EU.