jats:titleAbstract</jats:title>jats:pThis article furthers our understanding of the ontology of modern international relations by foregrounding the neglected structuring role of nationalism. Most accounts of nationalism in international relations reduce the phenomenon to a peripheral threat, whereby nationalism only seems to become relevant in moments when the international order is in crisis. In contrast, I argue that the ontology of modern international relations is inherently parasitic on nationalism. Leveraging on Jacques Derrida's writings on “hauntology,” this article recasts nationalism as a spectral logic that silently structures the ontology of modern international relations, even when it seems to remain absent and ineffective. In particular, I explain how the contradictions of nationalism become embedded in the concept of sovereignty, which serves as the ontological cornerstone of modern international relations. Transgressions of sovereignty are therefore not reducible to a tension between normative and factual levels, or logics of appropriateness and logics of consequences, but stem from the structural impossibility of the nationalist project itself. Viewed this way, the aporetic form of sovereignty is not merely a logical conundrum but a vital and productive ontological opening that sets international relations in motion.</jats:p>