Four days into the war in Ukraine, with the Russian advance slowed by unexpected Ukrainian resistance, Vladimir Putin made his first threat of escalation, implying the use of tactical nuclear weapons if NATO became heavily involved in supporting Ukraine. Since then, the threat of escalation has always been in the background - and has occasionally come to the fore.

The most recent example of this is the announcement from Moscow that Russian nuclear weapons will be forward-based in Belarus. These will mainly be nuclear-armed versions of the Iskander missile, which will be placed close to Belarus's western border with NATO states. Russia will also train Belarusian pilots in flying planes capable of carrying nuclear weapons.

Of itself this is not new. Nuclear weapons were based in Belarus during the Cold War, but in the current context the symbolism is clear enough: Putin is backing up his nuclear threats with more facts on the ground. Meanwhile, the United States is upgrading the nuclear storage facilities at Lakenheath, its main air base in the UK, meaning that tactical nuclear weapons can be based there again, after a 15-year lapse.

Putin's move comes at a time when Ukrainian forces are about to launch a major offensive that could take them very close to the border with Crimea. It is also the case, as Anatol Lieven points out in the current issue of Foreign Policy, that the political mood in Ukraine has become far tougher in recent months, with substantial opposition to any talk of compromise with Russia. Lieven quotes Oleksiy Danilov, secretary of the Ukrainian National Security and Defence Council, as saying: "If Ukrainian president Volodymyr Zelenskyi proposes peace talks between Kyiv and Moscow, he will commit political suicide."

Most Kremlin watchers take the view that losing Crimea would be a defeat too far for Putin, and the risk of it could push Russia into a direct threat to go nuclear. A sudden crisis could emerge at any time in the coming months. It would be the most dangerous nuclear-related situation since the 1962 Cuban Missile Crisis, yet the public mood in the UK and most Western countries does not recognise this as a major issue of concern. It raises the legitimate question, given the consequences of any nuclear attack, of why this is.

There are many answers to that, but two stand out.

One is the changing of the generations. To remember the full significance of the Cuba crisis you have to be in your late 70s or preferably older. The Cold War itself ended 33 years ago, so to have lived with the threat of a full-scale nuclear war, and what it would mean for the UK, you need to be 45 or so.

Back in the Cold War days, the UK government tried to convince the population that a nuclear war could be contained. The most laughable example of this effort was 'Protect and Survive', a public information booklet circulated in 1980, describing how the average house could be turned into a nuclear shelter.

It was beautifully parodied in Raymond Briggs' 'When the Wind Blows', while historian E P Thompson wrote a devastating counter to the government - 'Protest and Survive' - which did much to catalyse the vigorous anti-nuclear movement of the early 1980s.

At that time, though, the government persisted in its view that the UK could survive a nuclear war and still be a viable state. It was more than a decade later that there was an admission that a likely initial death toll would be of the order of 40 million out of what was then a population of 56 million. Britain would, to all intents and purposes, be a busted state, and many recent studies have suggested that the longer-term damage would be far greater, given the impact of a nuclear winter.

The second answer to the conundrum is much more to do with the present, and relates to a common public view that nuclear-armed states are invariably deterred from starting a nuclear war through risk of devastating retaliation. Deterrence through 'mutually assured destruction', the theory goes, was - and is - the name of the game and is sufficient to keep the peace.

This view is perhaps the biggest mistake of the post-Cold War era, and the fallacy is explored in a recent Culturico article. While Putin has made clear that the use of tactical nuclear weapons is an option, it is far less well known that the first use of nuclear weapons if losing a conventional war is NATO policy, and has been since 1968.

There is abundant evidence for this, and just two quotes from the Culturico piece are enough to get the flavour of it. One is from a US field manual from the early 1970s, which describes a typical package of nuclear weapons to be used in the early stages of a conflict:

"a group of nuclear weapons of specific yields for use in a specific area and within a limited time to support a specific tactical goal... Each package must contain nuclear weapons sufficient to alter the tactical situation decisively and to accomplish the mission."

"Accomplish the mission" means win a nuclear war. This is light years away from mutually assured destruction.

The second is a quote from a US general, Bernard Rogers, supreme allied commander, Europe, in an interview with International Defence Review in 1986. Discussing the circumstances in which he might be allowed to use nuclear weapons, he said his orders would be:

"Before you lose the cohesiveness of the alliance - that is, before you are subject to [conventional Soviet military] penetration on a fairly broad scale - you will request, not you may, but you will request the use of nuclear weapons..." (Emphasis in the original.)

Richard Norton-Taylor reminded us in an article just last week of the increasing evidence that the Thatcher government moved a nuclear-armed Polaris missile submarine within range of Argentina back in 1982. This was during the Falklands/Malvinas War in case the UK's task force was facing defeat.

Bringing us up to date, such a policy fits in all too closely with the UK government's current attitude to nuclear weapons, whatever its claims about stable deterrence. As Kate Hudson reported two years ago, Boris Johnson's government announced that Britain was increasing the size of its nuclear arsenal and was prepared to use nuclear weapons against a non-nuclear state.

Governments are content for people to think otherwise, but the harsh reality is that nuclear war is far from impossible and the conflict in Ukraine should be recognised for what it is, a very dangerous crisis that must be resolved by diplomacy, however difficult that is.

From openDemocracy