On the northern shore of Gare Loch, washed by salt waters that merge into the Firth of Clyde, is the naval base, Faslane, home to Vanguard-class submarines. The UK has four such Trident-carrying submarines, each armed with eight missiles, each of which carries three warheads. All together, currently, the UK holds a stockpile of 225 such warheads. This sea loch, and the wildlife it sustains, knows little of the destructive capacity contained within it.

Each warhead is said to be eight times as destructive as the bomb dropped on Hiroshima in 1945, which killed over 140,000 civilians. They are dark pearls of latent horror; symbols of humanity's power and folly.

This stretch of shoreline has, for this reason, been one of the most controversial sites in Britain since the 1960s – first home to Polaris, more recently Trident. Concern over the threat of nuclear weaponry, has waxed and waned with the changes in global politics.

The SNP's calls to scrap it were a key message of the Independence referendum, and one still repeated now. 2016 saw debate around whether the programme should be renewed at an enormous cost of £31 million for just the replacement submarines – CND estimated the overall cost would be more like £205 million. The House of Commons backed it, though only one Scottish MP voted in favour. Then, just last year, Boris Johnson announced a lift on the cap on the the number of Trident nuclear warheads it can stockpile by more than 40 percent by the middle of this decade. This ended thirty years of gradual disarmament.

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UN Elder Mary Robinson's view on this was clear, “While the UK cites increased security threats as justification for this move, the appropriate response to these challenges should be to work multilaterally to strengthen international arms control agreements and to reduce - not increase - the number of nuclear weapons in existence."

We are now in another chilling moment. Vladimir Putin's invasion of Ukraine, his threats of "consequences you have never seen", have meant that the word nuclear is on our lips again. The threat, which not long ago had seemed half-forgotten, a childhood nightmare demoted down the current list of existential threats, was there again: "the nuclear option". Might the Russian leader be mad and power-hungry enough to use it?

Ian Blackford recently confirmed the continuing support of SNP for getting rid of Trident, saying, "The idea that having nuclear weapons provides a deterrence that removes that threat is far-fetched, to say the least."

Nuclear weapons are often described as a deterrent. But do they really deter? That they have "kept the peace" is just a story, "a myth", not backed by evidence of cause and effect, as New York Times writer Ward Wilson has put it. He observed, "We don’t accept proof by absence in any circumstance where there is real risk."

Above all Faslane is a reminder of the ridiculous nuclear arsenal the world has built. We may have already clambered down from the global peak stockpile of nuclear weapons which existed in 1986, but there is a long way to go. Approximately 13,080 nuclear warheads exist worldwide and almost 90 percent of them belong to two countries: the United States and Russia. There are more than enough, if such maths made any sense, to kill every human on the planet, one hundred times over.

That fact, and Putin's terrifying recent posturings, should be a reminder that global nuclear disarmament must remain a key goal of our times.