International Legal Framework for Cyber Attacks in Outer Space:The Issue of “Use of Force”

The convergence of outer space and cyber operations has heightened risks of cyberattacks against space infrastructure. Such attacks, marked by non-physicality, cross-domain effects, and anonymity, challenge the prohibition of the “use of force” under Article 2(4) of the UN Charter. This paper examines the legal thresholds for characterizing outer space cyber operations as “use of force” by analyzing the UN Charter, the Tallinn Manual 2.0, and the doctrinal debates on intent, means, and consequences. It critiques the “scale and effects” criterion for inadequately addressing non-physical harms and attribution challenges inherent to cyberattacks. The study advocates for targeted reforms, including the development of specialized rules for outer space cybersecurity, enhanced multilateral cooperation to improve attribution mechanisms and the establishment of binding instruments such as a “Space Cyberattack Defense Convention”. These proposals aim to reconcile evolving cyber threats with jus ad bellum principles, offering both theoretical and practical pathways to strengthen international law’s adaptability to hybrid security threats in the digital and spatial domains.