The declaration of China’s Air Defence Identification Zone (ADIZ) over portions of the East China Sea in 2013 has often been interpreted by international relations scholars as an aggressive “land grab” in the sky. However, classical geopolitical perspectives of territory and control, despite their popularity when analyzing the politics of East Asia, fail to present a full understanding of ADIZ creation, adjustment, maintenance, and contestation. Rather than a problem created by the rise of China, conflicts over airspace are a regional phenomenon. By engaging with the critical geography literature on airspace, verticality, and space production, this paper theorizes ADIZs as the partial extension of state sovereignty via assemblages in response to the emergence of new vertical threats and opportunities. It then shows how the Cold War consensus on the function and performance of these volumes has broken down in East Asia, which has paradoxically encouraged both the expansion of ADIZs as well as their systematic violation. These “grey volumes,” which are characterized by debates over the legality, function, and performance of airspace, are explored in a case study of the ADIZs of Japan, South Korea, China, and Taiwan. Ultimately, these patchworks of ambiguous and overlapping airspaces are difficult to reconcile with classical geopolitics’ one-dimensional assumptions of sovereignty and territory.