Safeguarding Global Connectivity: International Law and Cyber Operations Against Submarine Data Cables

Submarine fiber-optic cables carry over 99 per cent of international data, yet the legal framework governing cyber operations against these systems remains underdeveloped and fragmented. This article examines the extent to which existing international law—specifically the United Nations Convention on the Law of the Sea (UNCLOS), the jus ad bellum regime, and international humanitarian law (IHL)—regulates non-kinetic interference with submarine data cables across peacetime, “grey-zone,” and armed conflict contexts. Relying on doctrinal analysis of treaty law, the jurisprudence of international courts and tribunals, Tallinn Manual 2.0 rules, and recent national cyber policy statements, the article advances three core claims. First, UNCLOS furnishes a differentiated but incomplete protective framework, providing relatively robust coastal state competences in the territorial sea while leaving significant enforcement and attribution gaps in the exclusive economic zone and on the high seas. Second, emerging practice supports an effects-based approach under which large-scale, intentional disruption of cable functionality may qualify as a “use of force,” and in extreme cases as an “armed attack,” thereby engaging the law on self-defence and countermeasures. Third, IHL’s treatment of submarine data cables as civilian and potentially dual-use objects entails constraints of distinction, proportionality, and precaution that remain insufficiently integrated into cyber operational planning. The article concludes by identifying targeted interpretative and institutional developments necessary to enhance the coherence and predictability of legal protection for submarine data cables without undermining navigational freedoms.