Neutrality used to be a European thing, but it is now in steep decline. If it were an animal, we’d have to declare it an endangered species.

For hundreds of years Europe was the ‘cockpit of war’, but if a country got sick of the unending great-power game it was sometimes possible to opt out entirely. If you declared you were neutral (and you didn’t live on the main routes used by the big armies), they might leave you alone for decades or even for centuries. Alas, those days are almost gone now.

With Sweden’s admission into the Nato alliance this week, only three neutral countries remain in Europe: Switzerland, Austria and Ireland. (I’m not counting mini-states like Liechtenstein, Andorra and Vatican City.) But I do owe my current state of contentment largely to the former prevalence of that endangered species.

It all started with my sudden need to spend a lot of time in Montreal. I had made a television series on war for the National Film Board of Canada that did very well internationally, but in the course of it I had fallen in love with the woman who directed three of the seven episodes (including the one that got the Oscar nomination).

That was my fifteen minutes of fame (the series was broadcast in 45 countries), but I needed to stay in Montreal because exiting her previous relationship was going to be a lengthy and difficult process. We therefore had to come up with a film project we could work on together in Canada – and given our recent focus it should probably be a military topic.

It was the time of the last big crisis before the end of the Cold War. If it had turned into a hot war, most of the intercontinental ballistic missiles and bombers would have been flying over Canada. (Look at a world map with the North Pole at the centre, and you’ll see why.)

Enough of those nuclear missiles and bombers would be intercepted over Canada to destroy the country even if it weren’t targeted directly, so membership in Nato wouldn’t save it. And apart from nuclear weapons, nothing hostile could reach Canada at all: Atlantic Ocean to the east, Arctic Ocean to the north, Pacific Ocean to the west, and US to the south.

So why was Canada in Nato? Emotional and historic ties, certainly, but you couldn’t make a decent strategic case for it in terms of national self-interest.

We had no strong opinions about Canadian neutrality either way, but it would be an interesting topic for a film. We pitched it to the NFB, and got the go-ahead to make a movie about neutrality.

We went to Switzerland, which has been neutral since the Congress of Vienna in 1815. We had a splendid open-air meal served on a white tablecloth in a Swiss mountain meadow and struggled to believe that we were in the midst of a serious military exercise.

However, Switzerland’s mountains are honeycombed with secret air force runways and military depots. All healthy Swiss men aged between 18 and 34 are obliged to do military service, and all are issued with assault rifles or pistols which they are supposed to keep at home.

We went to Finland, neutral by a treaty imposed by the Soviet Union a few years after the Russians attacked the country and annexed about one-tenth of its territory. Eighty percent of Finnish men do compulsory military service, the exercises usually take place in the forests near the Russian border, and the mosquitoes are bigger than anywhere else.

Sweden is much the same, just bigger and richer with more state-of-the-art weapons. It even manufactures its own combat aircraft, and its 165 fast attack boats are the coolest thing on the Baltic Sea. After 210 years of neutrality, it joined the Nato alliance this week.

And the one thing that became clear after that trip around the most prominent neutral countries in Europe was that neutrality is expensive. In the end we called the film ‘Harder Than It Looks’, because neutrals have to do everything for themselves. Typically they spend more on defence than allied countries, not less.

The film had its moment in the sun, Canada did not go neutral, and we all lived happily ever after. But many years later, when I was passing through some Canadian airport, I was hailed by a man who said that he wanted to thank me for putting his children through private school.

He explained that the film had frightened Canada’s Department of National Defence so much that they had given him a large long-term contract to provide Canadian schools with speakers defending the country’s Nato membership. It’s an ill wind that blows no one any good.

Gwynne Dyer’s new book is ‘The Shortest History of War’.