The expansion of digital technologies and social media platforms has challenged the classical foundations of media regulation under international law. Their decentralized and transnational nature, together with reliance on algorithms, has constrained traditional rules of media responsibility, which were premised on an identifiable editor, a defined place of establishment, and a clear nexus with States. This study rethinks the responsibility of media platforms for disseminating content that threatens international peace and security, asking how international law can move beyond exclusive reliance on the classical criterion of “effective control” toward a model based on a “duty of care and due diligence.” The study adopts a descriptive-analytical methodology based on international instruments, relevant judicial practice—including Delfi AS v. Estonia and the judgment of the International Court of Justice in Application of the Convention on the Prevention and Punishment of the Crime of Genocide (Bosnia and Herzegovina v. Serbia and Montenegro)—and contemporary legal scholarship. The findings indicate that platform algorithms contribute structurally to the amplification and dissemination of extremist and conflict-generating content, while a duty of care and due diligence may provide a basis for assessing State conduct and failures to adopt reasonable preventive measures against risks arising from platform activities. The study concludes that international law requires reconsideration of attribution, effective control, and structural responsibility, alongside a shift toward hybrid and preventive models of responsibility involving States, platforms, and international institutions, enabling international law to adapt to the realities of the algorithm-driven media age.