If there's one feature that defines Australia's strategic environment out to 2035, it is complex uncertainty. Not the supposedly inexorable rise of China, not the decline of America, not globalisation, not climate change or weapons of mass destruction or terrorism, but uncertainty.

The first instinct of many experienced security thinkers may be to dismiss this argument as, to use the vernacular, a cop-out. They will point out that this uncertainty argument is often adopted by defence bureaucracies to insist that, because we are living through times of unprecedented unpredictability and change, we need to modernise the military with a bit more of everything.

These critics may also emphasise that, if a government is meaningfully to plan serious changes to defence capabilities, which can take decades, it needs to avoid the uncertainty trap and instead begin with credible judgments about strategic trends, including linear projections of what other powers' interests and capabilities could look like 20 years from now.

But bear with me. What if, this time, complex uncertainty really is the order of the day, indeed, of the next two decades?

Globally and in our Indo-Pacific region, many elements of uncertainty are interacting, more quickly and more intensely than at any other historical phase I can think of (I invite ripostes to this judgment).

Moreover, for the first time in a long time, the future global and regional economic and strategic order is characterised on fairly much every side by fragility and doubt. I should acknowledge here that Ian Bremmer's recent book about the intriguing concept of a leaderless G-Zero world, Every Nation for Itself, has helped me consolidate my own assessments on this score.

The economic and political sustainability of China's great experiment is looking the shakiest it has been for a decade or more. True, even if Chinese growth stalled now, its strategic heft would be formidable. But Chinese power is winning neither friends nor trust in Asia, making this a less-than-auspicious time to talk about accepting a Chinese sphere of influence. And of course a worsening of Chinese internal fragility or weakness would prompt new kinds of anxiety among the neighbours.

There is tremendous debate and confusion about whether the US can bounce back quickly and sustainably. Most important for the present analysis, there is a question over whether it can come back strategically in Asia. But with a more judicious mix of force and diplomatic coalition-building than it has managed for some time, America is still uniquely placed to influence outcomes globally and in Asia.

In India, almost all the submerged obstacles to the rise of the second Asian giant – corruption, policy paralysis, violent internal unrest — seem to be surfacing at once. Meanwhile Russia, Japan and Europe show little sign of arresting their various kinds of long-term decline.

The place of second- and third-tier players in the global order, from Brazil to South Korea, Singapore to Sweden, Vietnam to Turkey, is still in flux, as Ruchir Sharma's book Breakout Nations reminds us. In a world of uncertainty and fragility, it is worth remembering that weakness is only relative and that the staying power of stable societies and resilient smaller countries can have its own often under-rated quality.

Closer to home, Australia may be recognising a need to deepen ties with Indonesia at the very time when that country and its leadership may turn out to be as friendly to Australia as they can ever afford to get. Around the near-neighbourhood, from East Timor to the South Pacific, there is every prospect of the kind of enduring or worsening state weakness that will lead to calls for renewed Australia security intervention. A full-scale stabilisation operation in Papua New Guinea should of course remain every Australian defence planner's nightmare.

In the Middle East, as my colleague Anthony Bubalo reminds us, there are at least three potential looming security crises, one of which – an Iran confrontation or war – could involve an expectation of an Australian deployment. Even as Australia 'transitions' out of Afghanistan and supposedly joins America's eastward (and our homeward) pivot, the prospect of our forces returning to West Asia again under the banner of the alliance remains genuine.

And a security crisis in East Asia – from the Korean Peninsula to China's perilous maritime edge — remains plausible.

At a global systemic level, too, there is major change and the multiplier effect of complex interactions of trends: the new-found confidence and rising expectations of middle classes, the destabilising impact of social media, new patterns of migration, and the as-yet-uncharted impact of new kinds of manufacturing technology which could yet alter the future of the big economies.

All of this has huge potential to affect Australia's strategic environment and security interests. The fact that these interactions and impacts will be exceptionally difficult to assess does not mean our defence planners can ignore them and focus sharply on reductionist projections of US-China competition.

This leaves me with two parting judgments (and yes, I am, perhaps conveniently, about to take a holiday).

First, while striving towards the Government's promised 2013 Defence White Paper, Australia's strategic policy community would do well to leaven its reading of contending linear and prescriptive accounts of China-US competition, however bold and readable they might be, with geoeconomic and geopolitical forays that go well beyond the comfort zone of traditional security thinking. They could do worse than start with Bremmer and Sharma.

Second, while there are no easy answers about how to prepare for complex uncertainty, one thing is certain: now is a bizarre time for an Australian Government even to contemplate winding back defence and security spending.

Photo by Flickr user katieharbath.