Securitization theory has long aimed to explain how security problems come to existence. Yet, limited by the notion that 'security is a speech act' (Buzan et al., 1998) the wide range of actors and the processes of collaboration, negotiation, and dissent from which securitization is conceived have been understudied. This article makes a claim to move beyond the speech act to conceive securitization as a discourse network and explore the chain of associations and propagation processes that lead to the formation of (in)security. We propose that securitization behaves as a complex system of coalitions where actors adopt (in)security beliefs from other actors and form network dependencies both in cross-sectional and longitudinal ways (Leifeld & Brandenberger, 2019). To substantiate this claim, the study combines quantitative text and network analysis to examine over 10 million Twitter messages shared by five actor groups in the months leading up to the 45th G7 summit: politicians and governmental institutions, the media, advocates, politicians' folowees, and citizens on Twitter. We find that securitization is constructed by networks of elite and non-elite actors who collectively contribute to the debate, helping to propagate the (in)security discourse.