Australia will spend $200 billion in the next decade, mainly on new submarines, frigates and jet fighters - just a few hundred of them. Each would be very expensive to replace yet will become very vulnerable to emerging technologies which by comparison will be quite cheap - in the millions rather than billions of dollars - expendable, and numerous.

New technology is not a new problem. For example, the allies began World War I relying on horses, but the war was won by tanks and aircraft.

Further, the problem is fairly well known. The trouble is an unwillingness by government, bureaucracies, defence forces and suppliers to accept the possibilities and do something about them.

The US and Australia are pouring billions into newer versions of old technologies in the face of emerging new technologies that will make them more vulnerable than they have ever been.

The big-ticket items, according to former staff director of the US Senate Armed Services Committee Christian Bose, are artificial intelligence, autonomous systems, ubiquitous sensors, advanced manufacturing, quantum science and cyber attacks.

These technologies will be as disruptive as Uber, Netflix, Amazon and Airbnb for the same reasons: wider reach and lower cost. Or in the case of the military, better detection, targeting and striking of both attackers and defenders.

The problem is not lack of money, but how the money is spent. There is plenty of money for defence in both the US and Australia. But our 2 per cent of GDP defence spend is just a figure with no guarantee of effectiveness.

Detection technologies against submarines threaten to make them so vulnerable as to be useless because of the almost suicidal danger to submariners. Information technology is being developed that will sort the "noise" of ordinary ocean waves from the tiny surface disturbance made by the passage of a submarine many metres below.

Combine that with cheap submarine drone technology to target and attack the detected submarine and the submarine becomes about as useful as a horse in 1918 against tanks. However, the asymmetry works the other way: the small and cheap makes the large and expensive more vulnerable.

It is akin to a few large blowflies being downed by a swarm of insecticide droplets from which there is no escape.

Further, it is more difficult if not impossible to monitor the construction or acquisition of these new technologies by nations or insurgents in the way that the construction of large vessels or nuclear facilities can be monitored.

Given the long lead for both US and Australian big defence projects and the rapid advance of other technology, you have to wonder why we have put $200 billion worth of eggs in so few baskets.

There are two main reasons for this policy blind. The first is that, in both nations, the two major parties (especially the Democrats in the US and Labor in Australia) are desperately fearful of being seen to be "weak on national security" and therefore have to go along with every extremely expensive development of a new version of old technology.

The result is very little public discussion or contest of ideas on national security. We saw this virtual silence in the past election. Moreover, this has become worse in the past few years with increased secrecy and reduced transparency and accountability about defence procurement, as evidenced by recent National Audit Office reports.

The second reason for the policy blind is that the defence bureaucracy and suppliers have so much invested in present thinking and spending.

Budgets and programs are developed over long periods and get locked in. The aim of the defence forces, bureaucrats, suppliers and politicians representing the states or cities where the equipment is built or stationed then becomes to keep each of these programs intact and funded.

In Australia, for example, it would be nigh impossible to knock out some submarines, frigates or strike aircraft to develop or adopt cyber defences or other new technologies, let alone knock out a whole program.

It means that any change in thinking would require additional spending on the new technology. That would be hard to get through budget expenditure committees and would in any event be resisted by defence bureaucrats and existing suppliers because it might result in a later cut to existing programs if the newer program eventually got a lot of support. Knock out any competition for funding is the game.

This shows that the recent huge boost to spending commitments on big-ticket defence equipment in Australia may in fact reduce our national security not increase it. This is because it eats up existing willingness and capacity to spend so that less is available to acquire new technologies or to rethink how we spend our money in the face of those technologies so that our national security can be properly addressed.

It also eats up public funds that could address some of the more pressing threats to national security - far bigger and more likely than the nation-state contests that the old military technologies are geared towards.

Cyber attacks on logistic supply chains are a significant threat. Critically, Australia has only about 20 days' worth of crude oil, petrol, diesel and aviation fuel in "stockpile" and about 60 days' worth of LPG.

So even though we do not need to rely on food imports, if we have not got the fuel to bring the food to the people - or critical medicines and other products - it makes our population fairly vulnerable. Any number of strike fighters, frigates and submarines would not address that matter of national security.

Nor could they address the most pressing issue of national security by far: the climate crisis and global heating.