There are four key realities driving our need for submarines as the AUKUS commentary rages on

Thousands of words have been written on the particulars of a nuclear powered submarine capability, what is necessary to acquire it, and the price tag, drawing out a range of critical voices. The discussion has revealed much about the national debate on defence and foreign policy.

But in this important discussion there are four key realities we can't afford to lose sight of.

The depth of cooperation with the UK, and particularly the US, required to make AUKUS work has been one prevalent focus of scepticism.

One thing that has become clear is just how little appreciation there is of how deeply intertwined Australia and the US already are.

Australia makes essentially none of our munitions (though we are trying), our Air Force would find it difficult to operate if separated from the ongoing US-led programs that underwrite systems like the F-35 fighter jet, and the major combat systems in our warships are American.

If you want a neatly boxed version of sovereign capability", the pre-AUKUS status quo isn't it.

Indeed, perhaps more powerful than insisting that we will never sacrifice sovereignty might be to admit that we exist in a world in which sovereignty in any strict sense is elusive. We might then be able to have a nuanced discussion about what options and alternatives we want to pursue.

Another prominent thread of critique has been the possibility that a future SSN, or nuclear-powered submarine, capability will allow Australia to play a role in distant wars, most obviously one over the status of Taiwan. That eventuality, and potential Australian involvement in it, is a sobering possibility. It should clearly be scrutinised.

What the understandable magnetism of a potentially catastrophic war over Taiwan has perhaps distracted from, though, is a longer and broader view of the region's future. China has (re)developed, but India, Japan and Indonesia are no bit players themselves. The region is full of big countries with growing economies and the dynamic politics that come with them.

We're still also discussing climate change as if it were a separate issue, but its impacts are a strategic problem, too. The recently released sixth assessment report from the Intergovernmental Panel on Climate Change affirms, yet again, a wide range of impacts with grim implications for Australia, maritime south-east Asia and the Pacific Islands.

Even if climate action is thankfully going to allow an escape from the direst warming scenarios, the impacts we've already locked in will contribute greatly to an unstable and unpredictable regional future.

Political violence of various forms, including between states, will surely be a part of the regional future we know we face.

Public opinion is a shifting and a tricky thing but governments and their publics have historically wanted options to deal with that likelihood.

Yet one view within the spectrum of opinion appears to be that we might just be able to sit out potential conflicts.

Perhaps we can deal ourselves out of any one particular clash, or even many of them.

But is it really credible that we can sit on the sidelines in general, across the sweep of our region and the long view of this century?

The answer to this problem need not look like buying and deploying SSNs, of course - that is far from an inevitable part of Australia's response. That is a choice we are making. But the debate of the last few weeks has revealed a deep discomfort with the idea that we will be forced to play a part in an increasingly fraught geopolitical environment.

Another prominent thread in the discussion has been an insistence from some that this deal is not part of any containment policy directed at China.

But if AUKUS is not about an attempt to maintain the political status quo, it begs the questions: what alternate vision of order in the Indo-Pacific are we willing to tolerate? What is China's place in that order?

To imagine an acceptable alternative order is difficult right now. Xi recently met Putin in Moscow, and the war in Ukraine rages on. But to think that in 10, 30, or 50 years Australia will have not had to face up to a profoundly changed regional order should self-evidently be wrong. That idea is surely as misguided as the notion that we can just sit things out and it will all pass us by.

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The AUKUS debate has thus also highlighted the implicit view held by some that we don't have to come to terms with a profoundly changed world, in ways more difficult than any capability acquisition.

We need strong military capability but we cannot solve the challenges we face through any defence policy. We will be faced with wicked foreign policy choices and Australia's sense of self will have to evolve.

As a country, we will need to be more nuanced than simply arguing for-or-against nuclear powered submarines and everything we might imagine them to entail.