Nuclear strategists refer to what is known as the stability/instability paradox.

It is a striking fact that when the USA found itself as the world’s sole nuclear power in 1945 it did not seek to use its monopoly to gain military advantage. But in any case, its monopoly was short-lived. By August 1949 the USSR had tested an atom bomb and by August 1953 a hydrogen bomb. In fact, the USSR lacked the means to deliver either of these bombs to the USA and it was only in 1967-68 that it finally achieved that capacity – which was why Nixon, arriving in power in 1968, became so determined on arms control and detente.

The general public did not understand this and from the 1950s on assumed that we all lived in the shadow of MAD – Mutual Assured Destruction. And, certainly, the USSR of the 1950s had the capacity to deliver nuclear bombs anywhere in Europe, if not to the USA. It was only when the USSR developed its SS-6 and SS-7 missiles that MAD applied to the USA as well.

The theory of MAD was simple. Nuclear warfare was so awful and its effects so irreversible that no one could really “win” a nuclear exchange. Even though the phenomenon of a “nuclear winter” was not then known, it was clear that provided both sides had second-strike capability, both of them would be reduced to radio-active ruin. Accordingly, no one could rationally wish to start such a conflict. So although, ultimately, the USA and USSR both had nuclear weapons, they were equally deterred from using them and this in turn guaranteed an uneasy peace.

This continued to be the case when Britain, France, China, India, Pakistan and North Korea all obtained nuclear weapons. In fact we now know that in October 1973 when the Yom Kippur war was going disastrously badly for Israel, the chief Israeli commander, Moshe Dayan, turned to the premier, Golda Meir, and asked whether the country needed to arm its nuclear weapons. Meir said no. But the point is that although Israel has never confirmed that it has the bomb, it clearly already possessed nuclear weapons by 1973. So, we are talking of a nuclear club of eight nations, so far – or even nine when South Africa briefly also had the bomb.

Thus far there has been no war between the major powers since 1945, a period of 77 years. So MAD certainly seems to work and thus to guarantee a certain stability.

However, the very fact that a nuclear war between the major powers is apparently unthinkable, also creates a certain instability for it leaves the field free for smaller powers to fight non-nuclear wars and, often, for the major powers to take sides in these wars and thus wage proxy wars, though carefully keeping them at a conventional level only.

Thus we have had a large number of smaller wars since 1945 and a number of major proxy wars – Korea, Vietnam and now Ukraine.

Moreover, the fact that escalation to the nuclear level is apparently ruled out actually encourages the warring parties to greater violence and to taking risks, wagering on the unlikelihood that their opponent will want to be the first to escalate to nuclear level.

Thus, to take an extreme case, Pakistan has more or less openly encouraged terrorist attacks on India, including the shocking attack on the Indian Parliament in 2001 and the attacks on Mumbai in 2008 in which 174 died and over 300 were injured. Everyone is aware that the most likely site of a nuclear war is Pakistan-India and accordingly huge pressure has been brought to bear on India not to retaliate in the way that it could. But as India gets stronger its restraint could well diminish and the risk of a major nuclear conflict there cannot be ruled out.

Similarly, North Korea has staged numerous and deadly attacks on South Korea, counting on their opponent’s determination not to risk escalation. In that case too, the unthinkability of nuclear war seems to license extreme and risky violence.

At the moment, of course, we find ourselves in exactly this situation in which Russian forces are employing extreme violence against Ukraine, including the systematic raping, torture and murder of civilians, but with Putin continually threatening recourse to nuclear weapons in an attempt to bully his opponents into not responding. Putin has even threatened the West that anyone “who stands in our way” (clearly meaning Britain and the USA) with “consequences which will be such as you have never seen in your entire history”, clearly meaning nuclear strikes.

Similarly, current affairs programmes in Moscow often refer to “the Japan option”, referring to the way in which the US summarily brought the war against Japan to an end with two atom bombs. The idea is that if Ukraine continues to resist so strongly, Russia could drop one or two atom bombs on, say, Kiev and Lviv, which would stop all resistance immediately. Ukraine and the major Western powers have clearly decided to call Putin’s bluff and do everything they can to support Ukrainian resistance.

It is a nerve-wracking situation. In effect the West has decided that Putin cannot be allowed to stage an unprovoked attack on a peaceful neighbour and win. But Putin clearly cares not at all for Ukrainian or even Russian casualties and politically he cannot afford to lose.

It was perfectly obvious that even many of his ruling group were surprised and shocked by his recourse to war. Should this adventure end in a Russian defeat or even a draw with many casualties – amidst a stricken Russian economy – Putin would not survive. So, should he fear his gamble is failing he might indeed go nuclear. No doubt the Western powers are already on full nuclear alert.

Putin’s war on Ukraine very much resembles Hitler’s push into surrounding areas of Europe. For quite apart from his defeat and occupation of France, Belgium, Denmark, Norway and Poland, Hitler wanted to absorb into Germany not only Austria but the Sudetenland (from Czechoslovakia), the Netherlands and Luxembourg, all of which were to become part of “Greater Germany”.

There were to be no more Dutch or Austrians: they were now all to be Germans. In addition, the remainder of Czechoslovakia was divided into Bohemia and Moravia and placed under a Reichsprotektor. Hitler proclaimed that “Bohemia and Moravia have for thousands of years belonged to the Lebensraum (“living space”) of the German people” – clearly presaging their effective incorporation into the Reich too. When Reinhard Heydrich took over control in 1941 he announced that “We will Germanize the Czech vermin.”

In the same way, similarly citing “truths” from the mists of history about Ukraine’s role in the birth of the Russian people, Putin is seeking not merely to conquer Ukraine but to incorporate it into Russia so that its people cease to be Ukrainians and become Russians instead.

The Russians talk of how they must “cleanse” Ukraine of its “vermin” which clearly means any democratic or Ukrainian nationalists, whom they weirdly call Nazis. Similarly, Putin continually tries to talk of the war as if it is a noble mission against Nazism: he calls the sanctions against Russia a “blitzkrieg” and so on.

For the Ukrainians the war is thus one for national survival. One can only speculate about Putin’s state of mind. He has taken an enormous gamble, citing as his justification what is thought to have happened in the ninth century. Like Hitler he believes he is the bearer of a great historic mission and that nothing must stop him – hence his continuous threats of nuclear war.

The greatest test so far has been the sinking of the Moskva, the flagship of the Russian Black Sea fleet. US intelligence has now confirmed that Ukrainian anti-ship missiles were responsible for this – and thus far US intelligence has been right all along the line.

Russia, on the other hand, has consistently lied about its intentions so although it has denied that the Ukrainians sank the Moskva, its credibility is virtually nil. It has now been revealed that US and British intelligence learnt definitively about the impending Russian invasion of Ukraine back in October 2021 and that the director of the CIA was sent to Moscow to reason with Putin. At the time, of course, Russia was insisting that its forces were merely conducting exercises and had no intention of invading Ukraine.

Russian forces in Ukraine have clearly sought to capture the whole Black Sea coast but have found even the smaller port of Mariupol a tough nut to crack. They have completely destroyed the city of Mariupol but even so Ukrainian resistance continues. Beyond that, however, lies the main prize of Odessa, a much bigger port. If Russia can capture Odessa then Ukraine will be deprived of its entire coastline and all its maritime commerce, reducing it to a landlocked state with its trade and communications throttled.

The plan, fairly clearly, was to use the Russian Black Sea fleet, led by the Moskva, to bombard Odessa and then launch amphibious landings to capture the city. The sinking of the Moskva has not only made that plan less feasible but perhaps impossible altogether, for Ukraine’s possession of anti-ship missiles (and Britain has sent Ukraine more and much more highly developed anti-ship missiles) is clearly a major threat to other Russian ships. One can imagine the fury which the sinking of the Moskva will have caused the Kremlin.

This lies behind Putin’s threat of “unpredictable consequences” – a barely veiled threat of recourse to nuclear weapons - if the US (and presumably others) continue to supply Ukraine with weapons. The US and UK (the other principal weapon-supplier) will undoubtedly ignore this threat. But the very limits of the stability/instability paradox will clearly be explored.