Recent military and civilian developments are deeply affecting our understanding of the scope, depth, and criticality of new strategic threats to countries, both in outer space and in cyber space. These “fourth and fifth domains” have until now largely been treated as separate realms by states and by intergovernmental organizations working to promote governance, policy and legal issues in each context. Yet outer space and cyberspace are better characterized as interdependent elements of a complex and continually-evolving nexus of activity for State and non-state actors.

This paper analyses the progress in the development of norms of conduct – whether binding or non-binding – for space security and cybersecurity, and argues for a dovetailing of efforts regarding certain of these initiatives. The basis for such an approach lies in the fact that satellite communications are overwhelmingly carried out through cyberspace, and as such are subject to the vulnerabilities and strategic threats prevalent in both realms. Efforts such as those under the aegis of the United Nations (UN) Office for Outer Space Affairs, its Office for Disarmament Affairs and its First and Fourth Committees; the European Union, the Council of Europe, the Organization for Security and Cooperation in Europe, NATO and the Shanghai Cooperation Organization have addressed a number of issues with ramifications in both the outer space context and the cybersecurity context.

Of particular concern are issues around the use of force by States and their right to self-defence under the UN collective security regime; and State responsibility and liability for activities causing harm in both realms. Moreover, just as States find themselves in a new threat environment in thespace and cyber contexts, commercial entities operating satellites that support critical infrastructure such as air traffic control systems, GPS, and telecommunication networks are increasingly vulnerable to strategic risks caused by hostile and malicious actors.