Gwynne Dyer is a Canadian-born independent journalist whose column is published in more than 175 papers in 45 countries.

“I saw in some of the newspapers they used the term ‘Sputnik moment’,” said General Mark Milley, chairman of the US Joint Chiefs of Staff. “I don’t know if it’s quite a Sputnik moment, but I think it’s very close to that. It’s a very significant technological event that occurred.”

Sputnik was the first artificial satellite, launched by the Soviet Union in 1957.

Shocked Americans responded by speeding up their embryonic ballistic missile programme. The tired old ‘bomber gap’ was replaced by the’missile gap’, more convincing although equally imaginary, and US spending on new weapons soared.

It may be happening again.

What got Milley’s attention last week was China’s testing of a hypersonic missile that flew all the way around the world, skipping along the top of the atmosphere unlike traditional ‘ballistic’ missiles that go very high (ca. 2,000 km.) and then come down steeply. Back over China, the hypersonic ‘glider’ plunged into the atmosphere and homed in on its target.

By then it had slowed down to five times the speed of sound, and as it neared its target it went into evasive manoeuvres – steep banks and turns – to evade any anti-missile defences. And it can carry nuclear weapons, of course.

It was a performance impressive enough to set all the chickens flapping in the coop, including General Miller. “It has all of our attention,” he said.

This is the new ‘strategic’ weapon that every big power wants for Christmas. China’s test guarantees extra funding for the American version, whose first test flight is only scheduled for late 2022. Russia already has an operational hypersonic missile, and India and North Korea are working on them.

But hypersonic weapons are completely pointless in a nuclear role, so why is there such enthusiasm for them?

Hypersonic missiles are definitely cool. They can fly all the way around the world and approach a target from anywhere.

Chinese hypersonic weapons could be coming up over the South Pole to attack the United States, for example.

That makes them harder to intercept, because the curvature of the Earth hides them until they are quite close to the target. They can also manoeuvre on the way in which akes them even trickier to stop.

But ballistic missiles can already come from any direction, thanks to the magic of missile-firing submarines. And hypersonic gliders are basically just glorified cruise missiles, although they are moving five to ten times faster. Harder to shoot down, again, but so what.

Forty years after Ronald Reagan’s ‘Star Wars’ fantasy, there is still no country that has anti-missile defences capable of intercepting more than a few ballistic missiles at a time. In a real nuclear war there would be hundreds coming, and the vast majority would get though.

So serious strategists don’t waste their time trying to build a comprehensive defence against nuclear-tipped missiles. The only real defence against a surprise attack is the guaranteed ability to retaliate with your own nuclear weapons even if the other side attacks first: deterrence.

Faster missiles, stealthier missiles, smarter missiles don’t make any difference. Deterrence is a business of numbers and brute force, and hypersonic missiles with nuclear warheads don’t change the rules. Air and space defence is always a matter of attrition, and some of the missiles (enough) will always get through.

The whole hypersonic game is a dangerous and needless complication of a deterrent system that has remained reasonably stable for at least three decades now. Enough already.

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