The military technology death spiral

The quintessential platforms of army, navy and air forces seem to get more and more expensive, and ever less affordable. This was sometimes described as a "death spiral" and may lead to a point when it's about time to give up on such a platform concept. 
I will try to offer a concise, illustrated explanation of this very important phenomenon. My model is simplified* and assumes among other things that there's always a counter to a counter possible.
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At first, let's look at a simple modelling of a spiral between attack and defence. A form of attack (or firepower) is introduced, which provokes a countermeasure that largely or entirely mitigates this capability. The response is an improved attack capability that overcomes the defence. Rinse, repeat.
This was seen in tank development, when penetrative ability of tank guns and protective ability of tank armour were competing. Alternatively, you could think of the tank's protection as enabling attacks and as anti-tank guns ' ability to penetrate the tank's armour as the defensive side.

(click on image for a bigger version)

The costs of attacking and defensive abilities escalate together with said abilities. A 3.7 cm anti-tank gun did cost much less than a 8.8 cm anti-tank gun, and 15 mm of steel plate did cost less than 100 mm of steel plate. My model assumes that capability and costs are proportional (normally costs rise more than proportionally) to reduce one layer of detail that doesn't matter right now.
You see an additional dimension in the next diagram; the utility or usefulness (for deterrence, in warfare or both).
This scenario shows a rising usefulness, as the platform becomes more capable over time. Still, the escalating costs may eventually exceed the usefulness in warfare. The entire concept of this platform (which unites offensive and defensive capabilities such as a strike fighter, a tank or a destroyer) should be questioned at the latest at this break-even point. Further improvements are not worth the associated expenses. Different ways of 'doing business' in war should be found. The platform that unites offensive and defensive abilities is likely already obscenely expensive at this point.
Many metrics could be used to describe usefulness, such as how deadly a platform is, but in the end this is not a value that can truly be calculated. The entire model does not offer a formula for calculation. It is meant to create awareness in the reader's mind about this break-even point and why it will be reached eventually.
The next diagram shows a different, more pessimistic scenario. The platform's usefulness in warfare actually degrades as its evolution is driven by the attack-defence spiral instead of by the mission.

Medieval knights were a good example for this. They were initially an all-round mounted force, but at the latest by the 11th century the weight of armour reduced their utility to a specialised battlefield shock attack force. The personnel also gained a high social status. Other cavalry tasks such as scouting or foraging were thus usually left to light cavalry. Horse cavalry only re-united into a unified cavalry in the 19th century when firepower had won so clearly over the cavalry's defence that the heavy cavalry niche became impractical.

The next diagram shows a special case in which the costs of a system escalate not as a sum of attack and defence, but are almost entirely about one of both. A fortress' costs are being driven almost entirely by its defensive qualities, and a land attack missile system's costs may be driven almost entirely by its offensive qualities. The break-even point will nevertheless be reached eventually.
Asymmetric arms races (such as cruise missiles versus air defence missiles) add another aspect. The offensive capability may keep getting funded for good reasons after its costs exceed its direct utility: Such a decisions an be justified by taking into account indirect utility; the expenses incurred on the opposing forces for defence against the threat. Land attack cruise missiles won't be self-defeating by high costs if the defence against them are more expensive missiles. Then the production of the threat system (cruise missile) would be escalated as long as the opposing forces waste their resources trying to build up a defence against it. Finally, the defenders may cease to throw more resources into a hopeless arms race and then the optimum for the threat system (cruise missile) would in theory exist: A maximised difference between the (sum of direct and indirect) utility and the (lower) expenses for it.
So in the end, the asymmetric arms races can be described using the same graphics, just keep in mind that utility = direct utility and indirect utility in such cases.
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Certain platforms -especially tanks- have been proclaimed "dead" when a new iteration of a counter looked particularly convincing, such as the rise of anti-tank guided missiles in the 1960's. But engineers usually find a new iteration that counters the counter, such as composite and reactive armours that kept 1960's anti-tank missiles from penetrating most of a 1980's tank's front. Potential technical counters are known to just about all forms of attack today. Likewise, counters to just about all forms of defence can be found.
I assert - and this model visualizes -  that the real death knell for a concept is not some spectacular-looking iteration of a counter to it: It's that the death spiral of escalating costs does at some point exceed the usefulness (the utility) of a platform. This doesn't necessarily stop the evolution, though. Usefulness in warfare cannot easily be monetised and compared to expected costs of a platform evolution step. We may - and likely do so regularly - keep going in the death spiral, wasting resources on platforms that have long become inefficient.

The exact quantity of iterations until the cost-utility break even varies.
The figures in the diagrams are symbolic.

You may use and modify the model with proper attribution (author Sven Ortmann, Defence & Freedom blog).
*: Models should be simple and reduced to one thought or essence when meant for explanation. Complicated models are good for simulation purposes only.


  1. Broadly speaking agree with you, but at same time aren't there cost-reducing technological breakthroughs at times too--e.g. drones for manned aircraft, reusable laser defenses for expensive missile defences?

  2. The laser weapons have low variable costs, but high fixed costs.

    The graphs above can be applied to one approach, such as the approach of "surface to air missile with rocket propulsion". A switch of the approach such as from heavy anti air gun to surface to air missile is not included in the model.
    Heavy anti air guns became unaffordable in face of the requirements against faster & higher aircraft.

  3. You looked at the decline of old systems. New systems might at first not yield much for the investment. This would create a peak condition, when a system is most cost effective and conditions that keep old systems in use, because despite dimishing returns on investment, the returns on investments into new systems don't yet outperform them.

  4. Arms Race does not have to work linearly with stable escalation, and points of diminishing or negative returns can be recognized without going into alternatives. This can be seen a lot of times in tank development, from excessive armor-arms ambitions of the landship committee down to FT-17. The development of Tiger 2, Maus, T95 is another example of gun armor escalation going beyond viability. In the history of warships, the tension between the gun armor arms race and the need for numbers resulted in tiered forces, from 1st/2nd/3rd rate ships of sail to destroyer cruiser battleship with different navies pick a different composition. The point of diminishing returns prevents infinite escalation to "absurd" gigantism but does not invalid designs around the optima.

    The death of a concept can be seem from asymmetric offense-defense cost curves: where a means of offense/defense/(other mission capability) is uneconomical across the entire range of options like armor versus missile design for warships. For existing weapons, new technological or occasionally social/political environment (things like normalization of unrestricted submarine warfare) has to generate these new offense-defense curve, otherwise a vehicles that have bad relationships with opponents at inception can be identified as a poor one before adaption.

    Economist's marginalist tools are pretty good for analyzing weapon systems, however even "trivial" cases require a pretty complex model to capture the impact across multiple interactions.

    1. idk about the ship of the line era but destroyer/cruiser/battleship wasn't purely a need for numbers. All did different roles & had different development paths, etc. A well balanced fleet with like 60 ships total vs a fleet 60 battleships will go in the well balanced fleets favour 9/10s out of 10.

  5. A remark relating to costs:
    The most commonly discussed figures typically relate to purchase cost.

    However, the overall cost, is a far greater multiple of that:
    Design cost, production and profit margin are sually counted in purchase cost.
    Training, munitions or fuel, logistics, maintenance and repair, upgrades over lifetime,... are massive cost drivers.
    And the more complex and lower number the item (high cost item), the more the overall cost is an iceberg.

    Ukraine shows relatively cheap drones are highly cost effective.
    Guided artillery and rockets may seem expensive, but relatively to giant navy ships or big bombers are bargain deals.
    In many countries, mine included, land forces are relatively neglected historically speaking. So are drones. In favor of high end fighters, ships etc.
    For the purchase cost, an f35 or frigate may be a good choice due to the versatility of the platform.
    But when comparing options, total costs are what should be compared, and this can get quite complex, and the values kept out of public view.
    Even other European countries, with the end of the cold war: massive amounts of tanks were removed from active service. Same with artillery, and conscription was removed.
    The air force and navy also suffered reductions, but I can't help but feel that accross the EU, it was the land forces that got the bigflgest cuts. Note that it is precisely land forces that make an invasion especially difficult.
    And a tank costs less than a plane or ship.

    I'm well aware you have articles advocating the almost removal of some navies; just felt total costs and the cold war proportion of cuts accross services were worth pointing out especially in this context.

    1. On the other hand, having tracked 60-ton land vehicles incurs additional expenses for support. You need stronger cranes, stronger recovery vehicles, stronger assault bridges, stronger pontoon/ferry equipment, additional fuel supply capacity, special driver training vehicles and trainers and suitable trank transporter trailers and tractors.

    2. I would also add that in order to employ tanks properly you have to spend money in training not only for the basics like driving, firing, etc. but doing manoeuvres at different levels like company, battalion, brigade that in tur increase maintenance costs.

      Without all of that you have a tank force but won't be very useful.