The liberal vision of the early 1990s envisaged the eastward extension of the Western European security community formed during the Cold War, based on intergovernmental cooperation and integration around the shared norms embodied by the European Union (EU), Council of Europe, and Organisation for Security and Cooperation in Europe (OSCE). Yet, transborder ethnic ties have remained a security concern within the “New Europe.” As well as the external challenges posed by Russia’s aggression against Ukraine, growing transborder nationalism exhibited by Hungary and other states has also become a focus of tensions within the EU. These intra-EU concerns, I argue, should be understood primarily as an issue of ontological security and as part of a multilevel security dilemma implicating states, EU institutions, and national minorities as security-seeking non-state actors. The article focuses on the Federal Union of European Nationalities—a transnational umbrella NGO that in 2013–2021 led an unsuccessful European Citizens’ Initiative named “Minority SafePack” (MSPI) calling upon the European Commission to legislate on firmer guarantees of minority rights within EU member states. Applying the ontological security lens to the study of MSPI, I illustrate how it reflects specific claims voiced by transborder kin-minority activists consistently over the past century, before analyzing the counter-securitizing arguments deployed against it by states. Although MSPI was approved with a large majority within the European Parliament, the Commission ultimately rejected it. I consider why this was the case, as well as the implications of the rejection for the in varietate concordia concept that supposedly undergirds the European project.