Armed forces in Canada are organised around the environment in which they operate. Cyberspace may not constitute a domain separate from air, land, and sea.

The traditional domains of warfare evolved as technological innovations introduced new ways for people and nations to exert physical force against each other. Each of the three key domains – air, land, and sea – presents unique challenges and opportunities and requires a different approach to military action. Operations on land differ from seaborne or airborne activities. Domains also share common qualities that are key to their classification. Each has a dimensional quality that military forces seek to control, with the goal of establishing freedom of action for friendly forces and denying the same to their adversary. Actions in any one environment might influence another, but in each the goal is to control a portion of that particular domain.

Actions in cyberspace can be a source of threats and can impact on other domains. However, despite the similarities, cyberspace challenges traditional military conceptions of environment because it is impermanent and malleable. A military cannot physically exist there, in the same way that an armed force can occupy a physical environment. The friction is not new. cyber war is an extension of theories and concepts that have historically challenged military doctrine; such as information warfare, command and control warfare, and network-centric warfare, which are not in themselves separate domains.

Reserving the label of a domain for the traditional environments of air, land, and sea reflects the accepted understandings of how to achieve military effects. The authors suggest that, as the understanding of and experience with warfare in cyber space evolves, so too might the definition of domains.

Definitional debates continue about how cyberspace fits into existing understandings of risk and response. While there is agreement that force and influence can be projected through cyberspace and there are some issues in common between addressing threats in physical domains and in cyberspace, the latter is not different enough to constitute a separate domain. Cyberspace might instead be understood as a supporting or enabling function for military capabilities on land, on sea, and in the air, more akin to a special operations role than a domain unto itself.