Mechanisms of threat: How Finland and Sweden abandoned non-alignment

Finland and Sweden are two countries with long histories of military non-alignment. In 2022, after the Russian invasion of Ukraine, both countries swiftly decided to apply for membership in the North Atlantic Treaty Organization (NATO). Why and how does such a drastic policy change come about? In this paper, I assess realist theory of threat and show that despite their apparent similarity, the reactions of the Nordic nonaligned to the Russian aggression differed significantly. Finland immediately sought protection from NATO, while Sweden attempted to continue non-alignment. Ultimately, the two countries reached the same alignment conclusion through different causal mechanisms.