IN a moment where daily collective death tolls, of varying amounts, are calmly announced on your teatime news, the incident had a certain grim charm to it.

Shot from the ferry window, the crew member’s phone pic showed a periscope sticking comically out of the grey waters. Close enough to ring with your holiday inflatable.

This was evidence, now fully investigated under an official accident report, that a nuclear-powered Royal Navy submarine had come within 50-100 metres of the Stena Superfast VII, during its North Channel crossing from Belfast to Cairnryan, on November 6, 2018.

A serious misreading of the positional data gathered by the submariners was found to be the cause. If the ferry’s officer of the watch had not taken “avoiding action”, says the report, there was “a serious risk of collision between a laden ferry and a submerged Royal Navy submarine.” Further recommendations will be made.

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But let the cold sweat trickle down your brow for a moment. The report begins with two columns comparing the craft. The military side is full of categories “not declared”, except when it comes to cargo: “not applicable”.

Really? The fact that a live nuclear reactor barrels around under commercial shipping lanes off this island, nearly hitting a passenger liner, is bad enough. But we’re also not allowed to know whether it was one of the four Navy subs that carry Trident nuclear missiles? Extremely “applicable”, in my view.

A brief survey of global submarine accidents over the last few decades, and your cold sweat will start to crystallise. Last year, we heard muffled reports of 14 Russian servicemen dying, after a battery exploded into flames on a nuclear sub in the Barents Sea.

Military officials told those attending the funeral in St Petersburg that their relatives had “averted a planetary catastrophe” before they died. The defence minister Sergey Shoygu said the onboard nuclear reactor was “operational”, as the crew had taken “necessary measures” to protect it.

And these are the ones we know about (assuming what we know from Russian media is hardly reliable). In 2017, under a release of declassified documents from the CIA, we discovered that a Poseidon-armed US nuclear submarine, and a Russian counterpart, had collided in the waters outside Holy Loch in 1974 (so significant that Henry Kissinger was telegrammed).

It’s less easy, in these all-seeing days, to hide incidents. So in 2009, when HMS Vanguard, (bearing 16 Trident missiles and 48 warheads) clattered into the French submarine Triomphant (bearing 16 M45 missiles and 48 warheads) in the Eastern Atlantic Ocean, we knew about it pretty quickly.

How do two submarines hit each other in an ocean? The technical answer is: precisely by being so stealthy, shielded and difficult to detect (including each other). But never mind a cracked reactor: on the British side of this Atlantic collision, the sub’s 48 Trident warheads equalled a destructive payload of 384 Hiroshimas. An accident of this kind, cascading into full disaster, only needs to happen once.

So now you know – yet again. As we huff and puff over mask wearing, teleworking and home-schooling, all the time our very modernity hangs by a slender thread (and has done for 75 years).

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Occasionally a pair of blunt, rusty scissors attacks the thread: thankfully, there’s a loose screw on the blades. So far, no snip, no fall, no obliterating smash on the floor below. Yet.

Ever since I was a young man, when the gravity of this situation sunk into me, I have always found a degree of sanity (literally) in the fact that I could vote for a Scottish party that implacably opposed the possession of nuclear weapons.

And that when its political aim of nation-state independence was achieved, that party (if it comprised a government) would use Scottish sovereignty to remove them from this territory. It felt, and still feels, like a crucial mental (even spiritual) resource. What could be more foundational for a new political community – to cast out instruments that threaten the lives of billions, and reduce these weapons’ credibility and relevance by doing so?

AND the truth is that the world is under even more extreme threat of the use of nuclear missiles than ever before. If you want a glimpse into the bureaucratic banality of evil, search for an essay titled “Wormhole Escalation in the New Nuclear Age” by Rebecca Hersman.

Peering through Hersman’s jargon, you begin to realise that there’s a new military logic abroad in the nuclear powers, called “dual use”. This is where “conventional” and “strategic” (meaning nuclear) weapons are being brought under the same active command systems. Worse, they’re also being linked into cyber-war and information-war strategies.

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The good old days, apparently, was when deterrence came from being a nation powerful enough to conduct a second strike (which would deter any aggressor from striking first).

The bad new days are when battlefield nukes are being deployed amid clouds of misinformation, deep fakes (simulations of political figures), the hacking of weapons software. The “wormholes” Hershman talks about mean the potential for various actors to punch their way through the usual power structures, landing their nuclear threats (or blackmails) on anyone’s doorstep.

“Wormholes are inherently, and indeed catastrophically, unstable,” concludes Hershman. “Whether in terms of [science-fiction] space travel or nuclear escalation, they seem best avoided.”

So rather than a nuclear-free Scotland being some kind of sandal-wearing anachronism, it is in fact as vital an issue for Scotland’s independent future as climate crisis, demography or automation. And one where the opportunity for global moral leadership is clear, should we wish to take it.

However, I’m amazed at the intellectual collapse that often happens in front of this issue. I hate to disagree with a comrade, but that most public of Scottish intellectuals Gerry Hassan tweeted something very regrettable at me this week.

“Why did Ireland as the Free State leave the UK debt-free? Because it leased three ports on its west coast for a period. Trident is a bargaining chip,” wrote Gerry. “Imagine an indy Scotland debt-free, able in its early years to eradicate child poverty and eventually be nuclear free. Independence involves strategic choices and timescales.”

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Seems reasonable, right? This is what a Scottish Government which was sharp in its realpolitik would do, yes? Except when the incident happens on your watch, and with your legitimation, Gerry.

We’re as likely to have a full-meltdown military nuclear accident in the early years of a “strategically” adroit indy, as we were in the last six decades. It only needs to happen once.

We are not short of procedures and expertise on how to safely but progressively remove Trident nuclear missiles, and their associated materials, from Scotland’s territory – first making them inert, then structurally dismantling and converting the whole system. Both Scottish CND’s Disarming Trident, and SNP CND’s Roadmap For Trident Removal, are authoritative and comprehensive policy documents, available on the web.

It would be the most serious and adult work an independent Scotland would ever do – and it would be the opening statement of our brand of seriousness to the wider world.

Nicola Sturgeon has embraced the scientific and administrative challenge of Covid-19 policy; I believe she was also CND before she was SNP. So I expect she would regard the execution of this aim as the most statesperson-like of acts.

Do we begin our independence shrouded in the ash of a future disaster, deriving dirty rent from the potential of sheer atrocity? Did we come all this way, to ethically collapse at the last minute?

It’s a near-joke periscope, popping out of the waves on the starboard side. But it’s also a warning finger. Bairns, not bombs. Not bairns riding on bombs.