The dispute was about territory – borders that were drawn almost a century ago by a Russian dictator, Joseph Stalin – and Azerbaijan had lost the last war and a lot of land.

So the Azerbaijanis spent a lot of money (they have oil), bought some key weapons (cheap Turkish-built drones), and took most of the land back. Human cost: around 5,000 dead on both sides, and a great many refugees. But at least it was about something real.

Now the United Kingdom is keen to buy some of those Turkish TB-2 drones, because they’re dead cheap ($1-2 million per copy), and they are very good at killing tanks. Armenia lost 224 tanks; Azerbaijan lost 36. But whose tanks is Britain planning to kill? Russia’s?

It’s 2,500 km.from London to Moscow, and most of the countries in between are part of the same NATO alliance that the UK belongs to. NATO countries have six times the population of Russia and ten times the GDP – and by the way, there are no territorial disputes between NATO countries and Russia. What are they all playing at?

You can see the same irrationality in the current weapons-grade squabble between the US Congress and the White House over next year’s defence budget. It is $740 billion, or $2,235 for each American man, woman or child.

That is more than the defence budgets of the next ten biggest-spending countries combined, although there is no evidence that the US government fears a simultaneous attack by Russia, China, India, Germany, France, the United Kingdom, Brazil, Saudi Arabia, Japan and South Korea.

Indeed, none of those national capitals is less than 5,000 km. away from the United States, and most of the distance in every case is open ocean. Only Mexico and Canada are physically able invade the United States, and either could be stopped with a few harsh words, or at worst by the highway patrol.

But what about nuclear weapons? We haven’t time to get into the arcane philosophy of nuclear deterrence, and fighting a nuclear war would actually be national suicide, so let’s just ignore the whole US nuclear establishment. The nuclear stuff in the US defence budget costs $98 billion, so how do you justify the other $642 billion?

Senate Majority Leader Mitch McConnell explained that the disputed defence appropriations bill “will cement our advantage on the seas, on land, in the air, in cyberspace and in space,” but you have to ask: an advantage that enables the United States to do what?

Stay in Afghanistananother year? The US couldn’t win there in nineteen years, but just one more year will do the trick? Deter China from militarising some reefs in the South China Sea? Well, not so much deter the Chinese (for the airstrips are going ahead on those reefs – China is also playing the ‘Great Game’), as harass and annoy them about it.

You can see why Armenia and Azerbaijan spend money preparing for war, but for the great powers it’s just silly. They have no disputes worth going to war for, and conquering any of them has been out of the question since the advent of nuclear weapons 75 years ago. Why are they still doing it?

There is the ‘military-industrial complex’ in every developed country, of course: millions of jobs and billions in profits. But that still depends on a perception of threat, even if the threat isn’t really there. What really makes this nonsense plausible is a very ancient mindset.

In the 1960s an Americananthropologist, Napoleon Chagnon, went to the Brazilian Amazon to study the Yanomamo, some 25,000 ‘horticulturalists’ (slash-and-burn agriculture plus hunting) living in many villages of around a hundred people each. Each village was absolutely independent, completely responsible for its own survival – and always potentially at war with every other village.

There was enough land and food for them all, and nothing to be gained by grabbing more territory. In fact, they left huge buffer zones between the villages to discourage raiding.

They invited other villagesto feasts, intermarried, traded with one another, made complicated alliances, all in order to shrink the risk of the chronic, devastating wars that could annihilate whole villages. And still the wars happened.

So the only safety lay in being heavily armed and implacably ready to take revenge, even though there was really nothing at stake that was worth fighting about. Deterrence, in other words.

It’s exactly the same for today’s great powers, even though the ministers for war and secretaries of state for defence no longer wear feathers in their hair and bones in their noses. Except on State occasions, of course.