Mike Kelly's got a plane to catch and a marginal seat to win, but offers some final advice for a defence minister: 'the first report you ever get in Defence on anything is invariably incomplete or wrong. Be very careful about rushing to judgement on anything'.

It's good advice for the vastly important and now ominously creaking defence portfolio. In an hour-long interview with both of Australia's prospective defence ministers, I've barely touched the surface of the many issues facing whoever wins office on 7 September. But I've heard enough to know that, either way, Defence will end up with a minister deeply passionate about the portfolio, knowledgeable about defence equipment, and in fast need of learning on strategic issues.

Both Mike Kelly and his opposition counterpart David Johnston have a deep knowledge of the Defence Department and the military. That's rare for a portfolio that sees more leadership churn than other areas of government. On average, Australian defence ministers (and most department secretaries) last only two years in the job. Their opposition counterparts last even less. Most defence ministers arrive to the job with plenty of knowledge of politics, but little of military matters, and never have time to get fully up to speed.

That won't be the case for Australia's prospective defence ministers.

Apart from a one-year stint working on agriculture, forestry, and fisheries in the Gillard Government, Dr Mike Kelly has been working on defence issues since 1987 – as a military lawyer, Parliamentary Secretary for Defence, and now Minister for Defence Materiel.

Senator Johnston also brings a deep understanding of defence. He's in the rare position of having had the shadow portfolio for five years and has amassed knowledge from endless senate estimates proceedings, visits to all the global defence manufacturing hubs of relevance to Australia, and military establishments all across the country.

Yet familiarity has not bred contempt and both Johnston and Kelly have a deep concern for the men and women of the Australian Defence Force. Three of them stare down from a poster in Kelly's parliamentary office with the challenge: 'what have you done for them today?' It's a message Kelly personally crafted through multiple iterations. Johnston too cares deeply for the men and women of the ADF. After reports soldiers had lacked combat support during an incident in Derapet, Afghanistan, Johnston designed a tactical force to better protect them. Even today he speaks most proudly of the part he played in bringing a counter-rocket system to the ADF's base in Tarin Kowt.

Both Johnston and Kelly have plenty to say about the equipment Australia will buy to modernise its defence force between now and 2030, and show an impressive technical mastery of the weapons of war.

Johnston steps me through me how the centre-barrels of our aging F/A-18 Hornet fleet are leading to a higher rate of unplanned maintenance, and why the katabatic winds of north-west Australia necessitate a turbo-fan-jet-powered solution for unmanned maritime surveillance. Kelly explains how composite material technology has a role in the global supply chain of the Joint Strike Fighter, an essential project because 'the future battlespace is going to be characterised by a a need to dominate the electro-magnetic spectrum'.

Both men are enthusiastic about the Joint Strike Fighter and the need for future air superiority for Australia. Neither is naive about the JSF delivery schedule or cost. Both underline the importance of a future submarine so that Australia can conduct anti-submarine warfare, something they see as Australia's critical contribution to maritime security. Johnston though is scathing of the inefficient sustainment of Australia's current Collins class submarine fleet.

When I ask both to explain Australia's military strategy, they show less conviction. It seems both of Australia's prospective defence ministers have inchoate views on Australia's military strategy now and in the future. However, both agree that no choice needs to be made between Australia's security alliance with America and its economic relationship with China.

Beyond that thought, what emerges from our discussions is a range of loosely connected observations on the big strategic issues that will guide Australia's future national security: the future of the alliance, shifting major power relations in the region, and the threats Australia will face.

To be fair to both men, its late in a wearying election campaign and neither is in an ideal position to discuss military strategy. Johnston, as the shadow defence minister, lacks access to much of the information necessary to understand Australia's strategic environment and military strategy. Kelly, as Minister for Defence Materiel, has had his vision consumed by non-strategic matters. But even still, I'm surprised by the reflexiveness of their answers when we discuss military strategy.

Tomorrow, what the prospective ministers think about strategy.