We learn from Liz Truss’s updated biography of her short time as Britain’s Prime Minister, ‘Out of the Blue’, that there was widespread concern in October 2022 that Vladimir Putin might use tactical nuclear weapons in Ukraine.
This could have been in response to the success of the then Ukrainian counter-offensive near Kharkiv in which the Ukrainian armed forces recaptured much ground previously seized by the invaders.
Apparently Ms Truss spent many hours in the latter days of her tenure in 10 Downing Street studying weather maps to see how Britain might be affected by the radioactive fallout from any such attack.
She even sent her Defence Secretary Ben Wallace over to Washington to consult closely with the US authorities such was her worry.
No doubt she had in the back of her mind the radioactive fallout pattern after the 1986 accident at the Chernobyl nuclear power plant in Ukraine.
Although the circumstances were not exactly comparable with a nuclear attack, and the equivalent power of the explosion measured only 0.3 kilotons (compared to a tactical nuclear weapon of up to 50 kilotons), the Chernobyl fallout reached as far as Canada.
Thankfully on this more recent occasion is seems to have all come to nothing, despite the Americans reportedly being “50% sure” of the possibility that such a weapon might be used.
Which begs the question why Putin did not resort to tactical nuclear weapons when his war with Ukraine was going so badly at that time.
And the answer is probably quite simply that even he did not want to take the risk of escalating the conflict into a much wider nuclear confrontation.
Even although Ukraine was not, and is not, a member of NATO and therefore Article 5 of the North Atlantic Treaty (“an attack on one is an attack on all”) did not apply, and even although Ukraine itself had given up all its nuclear weapons, Putin blinked.
He must have reckoned that a nuclear attack would have created such outcry and outrage from the rest of the world that the consequences for him and Russia could have been really severe. In particular he would have not wished the USA to become directly involved, which it might well have done.
There are nine nations in the world which we know have nuclear weapons. Most are of the strategic deterrent type, weapons of last resort when all else is lost and designed to destroy major cities. Britain’s Trident missiles carried by its nuclear-armed submarines (SSBNs) fall into this category.
The tactical nuclear weapons we are discussing here are battlefield weapons with a much lower yield and designed to be used against opposing armies and troops.
We know that Russia, the USA, and China have tactical nuclear weapons. Others may too but are unconfirmed. The UK does not - the last British tactical nuclear weapon, the WE 177 bomb, was withdrawn in 1998.
What do these events tell us about the possible use of nuclear weapons, strategic or otherwise, in the future? Nuclear weapons have only been used once, during the Second World War, when the USA struck Hiroshima and Nagasaki and brought that war to an end.
It is significant that they were used when one side possessed them and the other did not. Had Japan held its own nuclear weapons at the time the USA might have been much more circumspect.
Which is the essence on nuclear deterrence. Nobody wants to use them for fear of similar retribution in kind. Philosophically, then, they are both useful and useless. Having them prevents enemies using theirs, but using them at all is unthinkable.
What applies at the strategic level also pertains at the tactical level. If Putin had launched such weapons back in 2022 he would have opened the Pandora’s box of inviting others to do the same against Russian troops in Ukraine. And that was just a step too far, even for him.
It’s a mad world.
Lt Col Stuart Crawford is a political and defence commentator and former army officer. Sign up for his podcasts and newsletters at www.DefenceReview.uk