Keeping the country safe is the first duty of government and should be the constant concern of those with responsibility for our well-being.

I’m proud that the Abbott government successfully stopped uncontrolled people flows into our country that, in different circumstances, could have become an existential threat.

I’m pleased that we swiftly rose to the challenge of Islamist terrorism: with more airport security, more powers to detain terror suspects, new terrorist offences, more resources for police and intelligence, and a strong military commitment to destroying the death cult in the Middle East.

And I’m pleased that the Turnbull government has maintained these policies.

But I worry that a decade or so hence, maybe sooner, Australia might face a security crisis in our region and find that governments of yesterday and today had left their successors with inadequate means to deal with it.

When a Russian naval task force appeared to our north at the time of the Brisbane G20, I was told that neither of our two deployed submarines could shadow it.

They simply couldn’t get there in time.

It was a stark reminder of the limitations of a strategic deterrent comprising just six conventional submarines of which two are in deep maintenance, two are in training, with only two available at any one time – and limited by an underwater cruising speed of just 10 knots.

If the world were becoming more secure and if our allies were becoming more dominant, perhaps that wouldn’t matter very much.

This must be hoped for and it should be worked towards but it can’t be taken for granted.

Government’s job is to plan for the worst as well as to work for the best.

We will be judged by history as well as by our contemporaries and, at least where national defence is concerned, we have to think and prepare for the very long term indeed.

Defence capabilities can’t be summoned up overnight, as Australia discovered in 1942 when we had to send Wirraways against Zeros – before Spitfires and Mustangs could be brought into theatre.

That’s why it’s good that the Turnbull government is seeing through the process that my government put in train to select the next submarine for the Royal Australian Navy.

After years of procrastination, we desperately needed a government that didn’t shirk decisions about what our navy needs to safeguard national security.

I fear, though, that the right outcome from the submarine competitive evaluation process was not to pick the best of the three bids but to reassess what we were asking for.

As things stand, if all goes well, the first of the new subs will take seven years to design, seven years to build and perhaps two further years to bring into service.

If everything goes to plan (and it very rarely does in naval procurement) the absolute soonest we could get the first of our new subs is the early-2030s – to replace the Collins class subs that were originally supposed to start leaving service in the mid-2020s.

The Collins Class was designed in the 1980s, built in the 1990s, and then extensively modified and rebuilt in the noughties so that what was a very-good-sub-on-its-day could much more reliably take to sea.

As things stand, the Collins will need to be upgraded and modernised again while we plan for its replacement.

The whole point of the next submarine acquisition was to avoid the problems of the Collins – to find the submarine that could be brought swiftly into service with the least possible modifications – but what we have done so far risks an exact repetition.

We’ve based our proposed sub on an existing design but one that will need to be so extensively reworked that it’s effectively a brand new submarine and our intention is to build it entirely in Australia.

Although surface ships can be cost-effectively produced here on a continuous build basis, the primary object of defence procurement has to be the most effective armed forces – not domestic job creation.

We don’t build our jet fighters here, for instance, (although we do build parts for them) so why insist on a local build especially if there’s a big cost penalty?

A unique Australian boat is precisely what we wanted to avoid; but it’s exactly what we now face because of our insistence on a submarine that as well as being large, and long-range, was also conventionally powered.

The competitive evaluation process conclusively showed that there’s no such thing currently in existence.

All the submarines on which the bids were based are excellent for their countries’ needs – but none, it seems, for ours.

The Japanese sub lacked range.

The German sub lacked size.

And the French sub lacked conventional power.

But instead of changing what we wanted, we’ve decided – again – to bring an orphan submarine into being.

Instead of taking a small Swedish submarine designed for the Baltic and seeking to double its size and range to make it suitable for the Pacific – as with the Collins – this time we’re proposing to take a French nuclear submarine and completely redesign it to work with conventional propulsion.

This is so much more than the naval version of putting a four cylinder engine into an eight cylinder car because almost everything inside a nuclear powered submarine assumes unlimited power.

The resulting sub will have less power, less range, less speed and less capability than the existing submarine on which it’s based and it will come into service about a decade later than would be optimal at a time when strategic circumstances are changing against us.

Hence the basic question: why should we spend years designing a sub that’s inferior to one we could potentially have now?

It’s worth noting that Australia has not made a formal decision against acquiring nuclear-powered submarines; so much as studiously avoided even asking the question.

This was true of my government, like its predecessors, because – in hindsight – we may have overestimated Japan’s capacity to mount a bid and expected more than was reasonable of a submarine partnership virtually starting from scratch.

But now that the competitive evaluation process has established that there’s no conventional submarine to be had any time soon, this is a debate we should no longer avoid, especially as the strategic balance is shifting even faster now than last year’s defence white paper anticipated.

I’m not saying that we must go nuclear but surely we should at least consider the option before the opportunity is lost for another several decades.

The French-based design is hardly begun, let alone finalised. No contract to build has been signed and won’t be for years.

This is because it’s a completely new sub – inspired by, rather based on the existing nuclear model – that needs to be designed from scratch rather than simply modified to take a different engine.

So there is still a chance for further thought on this; there may even be a duty to consider Plan B should the design process be further delayed or should regional tensions show little sign of abating.

Our region is building more and bigger submarines.

Indonesia has two with three more coming. Singapore has four with four more coming. Vietnam has six and Korea has 14.

Japan has 19 advanced conventional subs.

India has two ballistic missile subs, one nuclear powered attack sub, and 13 conventional subs with six more coming.

The Russian Pacific Fleet reportedly has five ballistic missile subs, 10 nuclear powered attack subs and eight conventional subs.

Then there’s China with four ballistic missile subs, five nuclear powered attack subs and over 50 conventional subs with more and more coming all the time.

Our new subs are supposed to be “regionally superior” – including, presumably, to the sharply increasing numbers of nuclear-powered attack submarines that are based in our region.

Armed with the best US combat system, they should be; but they still have to be in the right place at the right time – and a conventional sub takes at least a fortnight to go from Australia to the South China Sea through which passes more than 50 per cent of our trade.

In other words, the regional submarine competition is vastly more challenging than it was when we last made a decision to go with a conventionally-powered submarine back in the 1980s.

Since then, both the United States and Britain have phased out their own diesel-electric submarines; presumably because there was nothing really needing to be done that nuclear subs or, perhaps, unmanned underwater vehicles couldn’t do as well.

Within the defence community, it’s sometimes said that our conventional subs complement the US’ capabilities because their ability to switch off their diesels and run on battery alone allows them to carry out closer undetected surveillance.

This is an important niche role but not a submarine’s main one: to inflict massive damage on an enemy’s ability to wage war.

I stress: I do not want to interrupt the process of acquiring new submarines given that it had languished for so long.

The design process with DCNS should continue and so should the build if that remains our fully considered assessment of what’s best.

But parallel with that, we should rethink what we want our subs to do, and what they might be up against in a changing threat environment, and explore nuclear powered options while our committed costs are only in the hundreds of millions.

In an increasingly uncertain and competitive strategic environment, can we afford to lack a more robust, sovereign (or semi-sovereign) capacity to deter and resist a sophisticated adversary; and it might be very hard to do that without subs that can range far and fast throughout our region.

Conventional subs need to surface frequently to recharge their batteries, need to refuel every 70 days, and can only briefly maintain a top speed of about 20 knots.

Nuclear powered submarines, on the other hand, can stay submerged as long as the crew can endure, never have to refuel, and can travel at nearly 40 knots.

In the Abbott government’s discussions about getting the best possible submarine for Australia as quickly as possible, we more-or-less assumed that our (currently limited) nuclear engineering capacity precluded that option.

Creating a nuclear industry to service subs here would take a decade, perhaps more, yet might turn out to be a lesser challenge than designing and building a new class of submarine almost from scratch.

Within the 15-plus years that it’s currently planned to take to get even the first of our new conventional subs into service, we could develop a nuclear servicing capability – and if we were to buy or lease a US submarine it could initially be supported at the American bases in Guam and Hawaii.

In the 1960s, we relatively swiftly developed a civilian nuclear capacity, mainly for medicine, centred on the Lucas Heights facility in Sydney; so it can be done if the will is there.

Not more robustly challenging the nuclear no-go mindset is probably the biggest regret I have from my time as PM.

The first question would be whether the US could provide us with their nuclear powered subs.

The US already provides Australia with its most advanced aircraft and tanks and its most sophisticated submarine torpedo weapons system.

The US has previously provided Britain with its most sensitive nuclear submarine technology.

There are said to be safety concerns about a country newly operating nuclear powered subs, but these could be allayed by seconding personnel from more experienced navies.

And a much more capable Australian submarine fleet – strong enough to be a game changer in any regional maritime conflict – would certainly help to address US concerns about countries “free-riding” on the alliance.

We have nothing to lose from starting a discussion on this issue with our allies and friends – Britain and France – as well as primarily with the US.

Then there’s the issue of bi-partisan support for a nuclear powered submarine.

In my experience, Labor has tried to avoid playing politics with national security.

If a strong national security case were to be made for nuclear powered submarines, I am confident that, at least under the present Labor leadership, it would get a fair hearing.

Labor has actually been stronger than the government on the assertion of freedom of navigation rights in the South China Sea.

Naturally enough, Labor is proud of its national security credentials and especially of its record under John Curtin and Ben Chifley and Bob Hawke.

Former Prime Minister Hawke has long advocated a bigger nuclear industry for Australia; and the South Australian Labor government under Premier Jay Wetherill would like to develop new industries to supplement the uranium mine at Roxby Downs.

Why not have a nuclear submarine servicing facility in that state – and the industries that would inevitably spin-off?

In any event, we’ll never know what Labor’s attitude might be without the public debate which I hope might now start.

Finally, there’s the question of cost.

Because of the engineering requirements, nuclear submarines are invariably more expensive to build and operate than conventional ones.

On the other hand, even nine (say) nuclear powered submarines could more than do the work of 12 conventional boats.

Much would depend upon the deal that the US might give to a close ally offering even closer interoperability and integration with American forces.

We won’t know until we ask but more burden sharing seems to be exactly what the new US administration wants.

We should never forget that our capacity to defend ourselves in ten, twenty or thirty years’ time, depends critically on decisions made now.

This is the area where our duty to our successors is most acute; this is the responsibility that the present owes to the future: not to compromise the nation’s defences a decade hence by short-sightedness now.

Like everyone, I hope that our country is never challenged and that our submarines never have to fight.

But the stronger we are, the more likely it is that we will live our lives in comparative peace.

Short-term politics should never constrain what’s needed for our national security; and on this subject, at least, we should be big enough to take the long view.