Australian elections are won or lost on domestic issues, but it is not quite true that the world outside was absent from the leaders' debate last night.

First, the so-called 'boats' issue – how to deter growing numbers of asylum seekers arriving by sea – is on many counts an international issue: it goes to regional diplomatic relations, Australia's image in the world, and changing conditions in countries such as Sri Lanka.

Thankfully, there was no reprise by Prime Minister Rudd last night of his insinuation some weeks ago that Opposition leader Tony Abbott's policy of 'turn back the boats' could lead to confrontation or even armed conflict with Indonesia. But nor did he try to explain himself when the debate moderator reminded him of this previous extraordinary assertion.

The crucial issue of this election should be getting Australia ready for the risks and opportunities of an Asian century. That's why I was struck by the uninspiring and noncommittal way both Mr Rudd and Mr Abbott responded to a question about the need and the timeframe for a second international airport in Sydney, Australia's largest city.

Of course this is, among other things, a parochial issue (and I admit I had trouble catching that bit of the leader's debate, what with all the aircraft noise over my Sydney neighbourhood). But nothing less than the Government's own Australia in the Asian Century White Paper has emphasised the importance of this country snapping out of two decades of indecision and inaction on a crucial missing piece of the nation's future infrastructure for engaging with Asia. It reads:

At Sydney’s Kingsford Smith Airport, limitations of existing infrastructure will start to have a sizable effect on airport operations from around 2015. In response to the growing capacity constraints around the Kingsford Smith Airport, we commenced a detailed investigation into the suitability of potential sites for a second Sydney airport...These strains will grow as demand increases. By 2025, our airports are expected to be handling three times as many international passengers...compared to the start of the decade, while air and non containerised freight volumes are expected to double. If left unchecked, this will erode productivity, the liveability and competitiveness of Australia’s cities, and our capacity to connect with the region.

By boat, by plane or by omission, the outside world will be part of our political debate however much we choose to imagine otherwise.