Domains of warfare seem to be proliferating rapidly these days. In Thucydides’ time, battles were fought on land and at sea—two domains. The combination of the two multiplied the complexity and confusion: at Syracuse (415–413 BC), for example, it led to the defeat of the foremost sea power of the day.

The use of airspace was apparent in its nascent form during the American Civil War (1861–1865), when balloons were used for overhead reconnaissance. But it was with the Wright brothers and the aeroplane that the atmosphere became something humanity could really use for transport, logistics and warfare. Air came into its own during World War I as a contestable operational domain.

And so there were three. More complexity and confusion.

Then, pushing boundaries, the Soviet Union launched Sputnik on 4 October 1957, and space became the new environment of human conquest. But while competition was high, space is a hard domain for humans to operate in. It remains an environment better suited to machines, and even those can prove fragile, susceptible to the growing density of space junk and the ravages of radiation. Still, the importance of space for military and civilian applications—the use of satellites for imagery and communications, for example—and not only for national prestige or scientific purposes, has led to its being acknowledged as a fourth domain.

In 2010, The Economist ^[1] declared that ‘warfare has entered the fifth domain: cyberspace’. In 2011, the US Defense Department officially incorporated ^[2] the new domain into its planning, doctrine, resourcing and operations; NATO acknowledged cyberspace as an operational domain in 2016. And perhaps because funding is seen to follow domain recognition, there has been some talk in the years since of a sixth domain, whether the electromagnetic spectrum ^[3] itself or, more scarily, the human mind ^[4].

But of the five domains now generally accepted as arenas of military operations, one is not like the others.

Each of the first four domains lies in the natural world. They are material and outside our control—we adapt to them—in a way that’s not true of cyberspace.

Fundamentally, cyberspace is a human-built domain. It has tenuous links back to the physical world: cables, data centres, the hardware of transistors and physical interfaces. But those, too, have been designed and built by humans. Its complexity differs.

And it means that rather than continuing to talk about simply operating in the fifth domain, we should be thinking about shaping it, and shaping it to our interests.

So far, articulating the nature of and doctrine for operations in the cyber domain has been hard. That’s not least because much of the underlying physical—and logical—elements are currently, and increasingly, conceived, funded and built by technology companies, not governments, and in foreign nations, reflecting commercial, not national, interests.

Despite having been drivers of the creation of the internet and facilitators of its use, Western governments have since exited this race. Now, to some degree, formulating cyberspace as an operational domain is an effort to reclaim lost ground. And not recognising the difference intrinsic to this fifth domain inherently limits our ability to understand and manage cyber issues, including in terms of strategic contests.

So let’s think through what a human-created domain means. We—humans—don’t simply operate in it; we shape it. That has immense implications for how we—the West—think about it in strategic terms. What shape bests suits our interests, and why? Conversely, what shape least suits our interests? And what does war look like in a human-constructed domain?

In the West, empowering individuals is intrinsic to our culture, politics and economics. We believe that, in the long run, the arc of history moves towards the light. (In the short run, even empowered individuals may need a helping hand.) So Australia broadly favours ^[5] an internet that is open, inclusive and centred on individuals and rejects one that is closed, exclusive and centred on the state.

Notwithstanding what President Donald Trump is seeking to do on the US southern border, Western societies don’t believe in ‘walls’.

Other cultures do. For example, in cyberspace, China has built its Great Firewall as a means of keeping external influence out and of controlling its own population. Just as the Great Wall of China proved irrelevant to modern technology, the Maginot Line was circumvented, and the Berlin Wall fell, so the Great Firewall has also weaknesses and will eventually fail. It is, like other walls, an artefact of human construction. But unlike other walls, it exists in a domain that is itself ‘constructed’.

Analogies from ‘real world’ domains immediately leap to mind. Remember, for example, the Dam Busters in World War II, which applied a carefully devised and targeted strategy for destroying walls. Or the leaky dykes in the Netherlands, where walls are weakened at multiple stress points and so increasingly susceptible to internal pressures.

In a number of respects, those are the sort of failures that concern us in the West, and quite rightly so. But we do not present the same target set: we haven’t constructed walls around our own societies to suppress and control our own populations. Our weaknesses may lie in treating foreign technology companies as being like foreign coalminers, though the government’s 5G decision suggests it’s not being drawn fully down that line.

Since the fifth domain is a human construction, we should work to redefine (and redesign) it in terms that we are most comfortable with. To borrow from the film Inception ^[6], we should aim to be like Dom Cobb (Leonardo DiCaprio) and his team—who are creators, architects, builders and shapers as well as operators in cyberspace—rather than accepting a reality imposed by others.