KEY POINTS:
A ship I once served in had a small brass plate on the bridge with a quotation from Thucydides, the Greek statesman, historian and seaman of the fourth century BC: "A collision at sea can ruin your whole day." It is still true.
It is harder to collide at sea than on land, since there are no blind curves and nothing moves much faster than a bicycle, so my normal reaction to a collision at sea is to think "How can they have been so stupid?" But here is a collision that beggars the imagination.
In the North Atlantic Ocean, on the night of February 3/4, at an undisclosed depth, the British nuclear submarine Vanguard and the French nuclear submarine Le Triomphant ran into each other. Both boats were "boomers", missile-firing submarines carrying 16 ballistic missiles, each of which can deliver several nuclear warheads at intercontinental range.
The North Atlantic is the second biggest ocean in the world. The submarines are considerably smaller: around 145m long.
So there they are, puttering along at six knots or less, with an entire ocean to play in, and freedom in three dimensions (they can go very deep if they want) - and they run into each other.
The damage was slight, but it ruined the day for two whole navies. How could they have been so stupid? All right, it's not quite that simple. The boomers - not just British and French missile-firing submarines but American and Russian ones too - congregate in specific parts of the Atlantic that are called "nesting grounds".
They need deep water that is relatively quiet, and they need to stay in range of their targets, so in practice they have only a quarter of the Atlantic to play with.
That still ought to be enough, but they are also deliberately running blind. If they operated their "active" sonar (the thing that goes "ping" in the war movies), they would detect everything on and below the surface for many kilometres around them - but everything they heard would also hear them.
They mustn't do that. Their job is to hide out in the depths of the ocean as a last-ditch nuclear deterrent that cannot be found and destroyed in a surprise attack.
So they run only the "passive" sonar, which listens to all the noises in the water but does not give away their own position.
Unfortunately, passive sonar cannot hear vessels that are not making any noise - and modern submarines are designed to be ultra-quiet. In this case, they actually closed to touching distance without detecting each other's presence, which suggests either that the two boats are astonishingly quiet or that there were two very negligent sonar operators.
The subs were obviously on courses that converged only slowly, because the damage was minor and all in the bows. If one had gone straight into the side of the other, however, then both of them could have been destroyed.
Down to the bottom go their nuclear reactors, plus anything up to 100 or so nuclear warheads on their missiles.
Both crews would have been lost - more than 200 men - but that would have been the end of it. None of the nukes would have exploded, and it really doesn't matter if there is a couple of tonnes of highly radioactive material scattered on the deep ocean floor hundreds of kilometres from the nearest land. Nevertheless, this is a useful reminder.
We have just been reminded that although the Cold War ended 20 years ago, all the nuclear weapons are still there. Not only that, but the submarine-launched ones are still out on patrol as if this were 1975. There is not a single good reason for them to be doing this, but nobody has told them to stop. Why not?
Because you don't know what the future might bring? I didn't say scrap the subs tomorrow, but tie them up in port and stop this nonsense.
If we all end up in a new Cold War one day, then okay, you can have them back, but why are they cruising around out there now?
You have to keep the crews trained? Well, train them in other nuclear submarines - or if they really must train in these particular boats, then TAKE THE MISSILES OUT.
It is not sane to keep deploying these instruments of mass death when no major power fears an attack by any other. And, by the way, if you could all agree to stop these ridiculous patrols, it would be a useful step towards the more sweeping measures of nuclear disarmament that all the great powers say they want, and that President Barack Obama has adopted as a serious goal.
Obama is the first occupant of the White House since Ronald Reagan with the vision to imagine a nuclear weapon-free future, and unlike Reagan he's smart enough not to let the guardians of nuclear orthodoxy talk him out of it.
He has a lot on his plate right now, but here's a step in the right direction: announce that the US Navy will no longer run "combat patrols" with its nuclear missile-firing submarines, and invite the world's other nuclear weapons powers to follow suit.
After this little demonstration of folly, they'd all come along pretty promptly.
