<p>Geopolitical tensions are increasingly aligning science and technology (S&amp;T) policy with national security priorities in several Western countries. After decades of actively encouraging international research collaboration and academic mobility, Canada has introduced new policies and guidelines to protect university research in response to national security concerns—reflecting similar developments in the United States and among its allies. Using the theoretical lens of institutional logics, we argue that these changes signal a cultural shift in the collective understanding of what constitutes appropriate and legitimate action. By examining policy developments and the evolving Canada–China relationship, we show that domestic factors—such as reframing China as a hostile actor, identifying specific threats to academic science, and an increased political focus on foreign interference—have legitimized the adoption of more assertive research security measures. Contributing to the international debate on the securitization of academic science, we identify two recent stages in the evolution of research security initiatives in Canada. The first stage focused on raising awareness and educating stakeholders about research security. The second stage, beginning in 2024, marks a decisive shift toward regulating international research collaborations. This stage is defined by the explicit identification of research threat actors and the establishment of boundaries in S&amp;T fields considered at risk, representing a significant departure from decades of the largely unrestricted promotion of international research partnerships.</p>