It’s easy to see why the Indo-Pacific concept is so popular in both Canberra and Washington. Managing China’s rise would be much easier if East Asia and South Asia really do coalesce to form a single integrated strategic system, because in that system India and China would almost certainly be primary strategic rivals. India would therefore hopefully function as a counterweight to China, balancing and limiting its growing power, helping America to persuade or compel China to drop its challenge to the US-led regional order and restoring Pax Americana.

But just because strategic rivalry between China and India might suit us doesn’t mean it’s going to happen, and just talking about an Indo-Pacific strategic system doesn’t make it real. We need to look more closely at whether a single Indo-Pacific system really will emerge across the Indian and Western Pacific oceans.

Andrew Phillips offers some key reasons to doubt that the Indo-Pacific can or will function as a single system, but I think there’s another one that deserves attention. It concerns the choices that India and China each have to make about their future relations with one another.

Why the focus on choices? Because our concept of ‘strategic system’ is something of an abstraction. A strategic system is simply the product of the aggregate of choices that each country makes about the countries it focuses on strategically. Countries don’t become strategic rivals because they’re part of the same system: they’re part of the same system because they choose to be strategic rivals. There will be an Indo-Pacific strategic system if India and China choose to be primary rivals, and there won’t be if they don’t.

Sometimes those choices are forced on countries by geography, but not always. Japan and China can hardly avoid primary engagement with one another strategically. But geography doesn’t compel India and China to engage strategically the same way. They have a wider range of choices.

That might seem surprising, because India and China share a long and contested land border. But it’s perhaps the most militarily impermeable land border in the world. It’s impossible for either country to project land forces over the Himalayas on the scale that would be needed to have any strategic impact on the other. It stands as a barrier between them, not unlike a major ocean. As a result, India and China relate to one another strategically mostly as maritime powers—as the expression ‘Indo-Pacific’ tacitly implies.

That means they do have choices about how directly they challenge one another’s core strategic interests. Of course two such powerful states are going to be rivals to some degree and on some issues. But their rivalry won’t create a single Indo-Pacific strategic system—and help us manage China’s rise—unless it engages their core strategic interests.

My hunch is that they won’t contest one another’s core interests, become primary strategic rivals and create an Indo-Pacific strategic system unless one or both seek to contest the other’s primary position in their respective ocean approaches. In other words, India would have to seek a major strategic position in the Western Pacific, or China would have to do so in the Indian Ocean, or both.

I think it’s quite unlikely that either will seek to do that. First, because each would find it very hard to project and sustain strategically significant maritime power into waters dominated by the land-based sea-denial capabilities of the other. They’d each face the kind of A2AD challenges that America faces today in the Western Pacific.

And second, because it’s not clear why they would want to try in the first place. Neither side needs to dominate the other’s sea-space into order to achieve their key objectives. Each will recognise the other as a formidable adversary. Why would either take on such a country as a primary rival if they don’t have to?

Some will argue that China at least has no choice but to become a major meantime power in the Indian Ocean to protect its sea lines of communication there. I don’t see the vulnerability. Since the Napoleonic Wars, no major power has sought to interdict the trade of another major power except in a World War. That’s globalisation and interdependence at work. China’s sea-borne trade, like everyone else’s, is protected by the mutual dependence that we all have on trade. It doesn’t need to challenge India in the Indian Ocean to defend it.

Of course it’s possible that one or both countries might mistakenly launch a costly strategic contest that they could and should avoid. But we can’t bet on that. It’s more likely that they’ll tacitly agree to stay out of one another’s regions. In that case, and judging, as I do, that the US-led order in Asia doesn’t endure, we’re likely to see separate Indian Ocean and Western Pacific strategic systems dominated by India and China, and separated by the line running from Myanmar through Malaysia and Indonesia down to Australia.

If that happens, Australia will be in an interesting position on the boundary between the spheres of influence of two great powers. That will offer up both risks and opportunities. Our policymakers and analysts should spend their time better exploring those risks and opportunities and what we can do about them, rather than assuming that India will allow itself to be played as a card in America’s contest with China.