Vladimir Putin’s deployment of force has tended to work out for him during his 20 or so years at the top: in Chechyna, Georgia, Syria and the eastern part of Ukraine.

He has Abkhazia, South Ossetia, Donetsk, and Luhansk, and there is no explanation of his drive towards Kyiv other than to effect the overthow of Ukraine’s government, the installation of a puppet regime, the dissolution of the country into a Greater Russia – and the pulling of its democratic neighbours into his authoritarian orbit.

As Jeremy Black reminds us today on this site, Ukraine is roughly 200,000 square miles large, and Putin has deployed some 200,000 troops near and within in.  The numbers make sense only if he was expecting a quick win and mass capitulation.

Such a rapid victory would have left the western powers with no time and little incentive to form a united front and impose meaningful sanctions – in the absence of which his autarchic state, now buttressed by an alliance with China, would be able to ride out economic and political pressure.

But there has been no swift victory.  Kyiv remains unconquered.  There has been no mass capitulation.  Ukraine’s armed forces have resisted bravely and Russia’s have proved vulnerable.  There is a united western front, with Germany now on board, at least for the moment – an astonishing departure from its entente with Moscow.

There are meaningful sanctions.  However self-enclosed Russia may be, and for all its alliance with China, their effects will be felt – by its people, who will be poorer at home, and its elites, who will become pariahs abroad.  No wonder Roman Ambramovitch tried his recent manoeuvre at Chelsea.

Putin has failed to cow his neighbours: Sweden and Finland turned up at a NATO summit.  He has complicated his developing relationship with Turkey, which says it will limit Russian ships entering the Black Sea.  And while China is repeating Putin’s talking points, it is uneasy at his treatment of a sovereign state.

Even Switzerland has broken with its neutrality to adopt sanctions.  The backlash against Putin’s war extends to culture as well as politics: Russian football clubs have been suspended from all Fifa and UEFA competitions.  The daughter of his own press secretary put up a “No to war!” post on Instagram. 

Putin will care nothing for public protests among Russia’s people: over two thousand have already been arrested. Its military, security and money elites are a different matter.  Tyrants fear coups and, when it comes to them, Russia has form.

The picture of a gambler whose bet has gone wrong is familiar, but it is a feature of some punters that they double down on their losses, especially if they fear losing face.  What does doubling down look like in Ukraine?  The atrocious answer is evident this morning.

The original Russian rush to Kiev and other key cities was slowed by Ukrainian resistance and other factors: fuel shortages, poor co-ordination, a lack of air cover.  So Putin is beginning to escalate the missile and aerial bombing of cities, in order to terrorise the population, clear the way for his troops and collapse Ukraine’s Government.

It isn’t yet clear whether Russia is using cluster munitions in Ukraine as it did in Georgia and Syria, But Karim Khan, the chief prosecutor of the International Criminal Court, says he will begin a war crimes investigation as “rapidly as possible”.

Meanwhile, ships belonging to NATO members risk being caught up in the hostilities. Reports of a Russian attack on a Romanian chemical tanker turned out to be inaccurate, but it is not at all hard to imagine such an event happening.  And Poland risks being drawn into the conflict as arms are supplied across its border.

In short, the prospect before us is months, if not longer, of atrocities followed by repercussions: horrific pictures flashing up on social media in real time, together with desperate appeals from Ukrainians; Brits preparing to fight there, arms being smuggled into Ukraine, talk of no fly zones.

And since sanctions cut both ways, and Putin won’t simply take them on the chin, the hot war in Ukraine is likely to be supplemented by a lukewarm war at home – complete with shortages, cyber attacks, disinformation, economic hostilities, closures and price spirals.

Since these risks are real, it’s imperative that Ministers think strategically.  Putin’s war can end only in one of three ways (other than occupation): defeat, withdrawal, a coup, or some combination of the three.  Outright defeat looks unlikely, and withdrawal scarcely less so, at least in the short term, especially from the eastern parts of Ukraine.

A coup may be no less likely than those two other possibilities, and would not be without its risks.  But western policy must aim to keep the possibility of a putsch alive, as Russia’s elites come to terms with the consequences of war.  Which means holding open an exit door and pointing them towards it.

The Government can’t compromise on support for Ukraine’s government, including the provision of defensive military equipment.  But it’s vital for Ministers to be clear about what we are and aren’t committed to.  Ukraine is not a member of NATO to which we have obligations under Article Five of its charter.

That should rule out participation in any no fly zone, which would require shooting down Russian planes: an act of war.  Clarity requires not encouraging martial Brits to freelance in Ukraine, and using the charge of war crimes with precision.

A fatal mistake was made in the aftemath of the Iraq War – namely, the de-Baathification of Iraq which, by removing all public employees who were members of the party from their positions, set the scene for the breakdown of order. A lesson from the experience is: target your measures.

The more widely charges of war crimes in Ukraine are hurled, the less incentive Russia’s military will have to break with Putin.  To maximise the chances of that happening, however remote they may be, it will be essential to have a message for the country’s elites, and stick to it.

What would this be?  It would begin by trying to reassure the Russian people that our dispute is with their leader, not them.  Boris Johnson was right to warn in the Commons against Russophobia – all too easy a trap to fall into by means of manoeuvre for political advantage, a careless tweet or real passion in the wake of atrocities.

It would offer the phased easing of sanctions against the phased withdrawal of troops.  It would refuse to recognise the validity of Putin’s puppet states in Ukraine established by force.  But it would entail a plan for the gradual demilitarisation of the region, and mechanisms for arms control.

If Putin truly is a gambler whose bet has gone wrong, is it really so hard to understand why he risked it?  It was right for Britain to avoid being drawn into Syria’s civil war, but he will undoubtedly have read avoidance as weakness.  Elsewhere, the culpability of the West in more clear-cut.

The prospect of NATO membership was dangled before Ukraine, but NATO’s biggest member led the charge to exit Afghanistan.  So was the prospect of EU membership while its leading member cuddled up to Russia. Putin’s latest venture in Ukraine has led to severe sanctions but his previous one led to nothing very much.

So it’s all the more important now to think clearly about what we should do and can’t do.  We must keep pointing Russia towards the way out, even if Putin is too mired in blood to take it.