Touring Normandy beaches shortly after D-Day in 1944, General Dwight D Eisenhower reportedly said, ‘If I didn’t have air supremacy, I wouldn’t be here.’

Today, space power has achieved the decisiveness of air power, and space, like the air, should be regarded as a warfighting domain.

Classifying the domain as a warfighting one furthers a nation’s ability to coordinate its capabilities, resource these efforts and requirements, and signal sufficient resolve – paving the way for credible deterrence. A warfighting designation serves to elevate the domain to that of air, sea, and land, recognising it as an environment in which conflict is occurring already, not merely an enabler for other domains. This in turn supports doctrinal legitimacy and helps justify space capability acquisition.

Many countries are yet to fully pivot to labelling space as a warfighting domain. In some instances, this has been intentional, through fear of promoting militarisation and a perceived escalation of military space activities. But the classification doesn’t create conflict; it helps create a framework of understanding within which conflict can be deterred, responded to and constructively bounded.

The space domain’s growing influence came to the forefront of public consciousness in 2018 when the United States announced work to establish a sixth branch of the armed forces, the US Space Force. The first administration of Donald Trump had defined space as a warfighting domain in the same year.

This was a strategic shift and escalation from previous labels of ‘operational domain’ and ‘supporting domain’, treating space as an enabler for operations on sea and land and in the air. Australia and NATO still refer to space as an operational domain.

In 2025, when testifying to the US–China Economic and Security Review Commission, General Chance Saltzman, chief of space operations for the USSF, took the opportunity to clearly isolate and reflect on the US’s nomenclature shift.

He said it testified to the tremendous change that had taken place, from when space had been treated as ‘a benign environment’ that reflected its use ‘as a strategic resource rather than a warfighting domain’ to a time now when adversaries’ space capabilities posed ‘an incredible threat to the rules-based international order.’

A country may operate militarily in space without calling it a warfighting domain. This was a rational ambiguity when space actors were few and actions were constrained, before the realisation of important technological advances. But this is no longer the case.

Space is no longer a distant frontier; it is part of the infrastructure of modern life. Once the preserve of two superpowers, activity in space has seen radical growth this century, including much wider military activity.

A bellwether for this new era, the 2026 edition of the Secure World Foundation’s Global Counterspace Capabilities report, tracked information on military capabilities being developed by 13 countries. These capabilities extend from electronic warfare to direct-ascent anti-satellite weapons to co-orbital spacecraft capable of grappling with other satellites.

We are also seeing grey-zone warfare on space-based and ground infrastructure increasing in frequency.

Inspector spacecraft play games of cat and mouse in orbit; some are selectively showing off or masking ever growing capabilities for rendezvous and proximity operations, signals interception, space domain awareness and more.

NATO, which began calling space an operational domain in 2019, has since found itself raising alarm at persistent space-related actions by Russia in the past few years. This was headlined by a major cyber attack on civil and military space infrastructure preceding Russia’s full-scale invasion of Ukraine in 2022. NATO also suffered from Russian satellites jamming positioning signals.

A response to such activity has been increased information sharing and disclosure of on-orbit activities among allies, partners, industry and media. This is supported by new and growing forums, such as the international Combined Space Operations initiative, which has 10 partner nations and is focused on space security collaboration.

While enhanced cooperation is a critical step towards establishing credible deterrence, it is equally important to have language that matches. The ambiguity of the ‘operational domain’ label is no longer fit for purpose. It plays down the reality of what is occurring today. Language matters, including for decision makers.

It also matters diplomatically, and a pragmatic shift in domain classification would not prevent anyone’s continued efforts in diplomacy relating to space.

The labelling of space by Australia and others as a warfighting domain would be a pragmatic step. Ambiguity in this instance has not prevented space from becoming a warfighting domain in fact if not in classification.