Ukraine is now seeing the worst atrocities in Europe since the Second World War

A murderous attack using cluster bombs on a railway station, killing upwards of 30 refugees; 130 civilians kept in a stinking cellar, with the dead piled up in a corner; random shootings and rapes: the kinds of war crimes that Boris Johnson describes as being not “far short of genocide” are now routine in Ukraine.

Because of the scale of the war, it exceeds the horrors of the civil wars in the former Yugoslavia. Thus, these are the worst atrocities seen in Europe since the end of the Second World War.

In many ways, they seem even more senseless than might have been feared – even after witnessing the actions of Russian and Russian-backed forces in Chechnya, Georgia, Syria, and eastern Ukraine and Crimea in 2014. It is worth considering why Vladimir Putin’s soldiers are behaving in this way – and what might be the appropriate military response.

Indiscipline, poor leadership and toxic propaganda have obviously undermined the moral compass of the Russian forces. This was reinforced by the simple calculation that their evil would not be discovered – they did not expect to have to cede the territory they had freshly occupied. The scenes found by independent journalists on the ground suggest that the troops evacuated in a hurry, and had little chance to disguise the evidence of their crimes.

Second, the Russians have proved themselves so inept at conventional combat under the usual rules of war that they have had to fall back upon terror – every outrage, from blind missile attacks to the use of rape as a weapon of war, has been designed to terrify the Ukrainian forces and, especially, the civilian population. Citizens are beaten and frightened into submission in the most cowardly way possible. It hasn’t worked out especially well for Russia, but it’s all they’ve got.

The danger is that the escalation in the atrocities, as they’re discovered and documented, so enrages western public opinion that pressure grows on governments to act militarily. A full-scale intervention by Nato forces has obvious attractions, and would deliver an early end to this war of aggression. But it would not humiliate Mr Putin, who would use it as proof that the Americans had wished to control Ukraine, and its imaginary Nazi regime, all along.

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In the end, it will not be President Putin but the people of Russia who will end such wars and put their country on the path to a better, more nuanced approach than that being pursued now. Incrementally, more useful military hardware is being supplied to Ukraine, such as the Czech and Slovak surplus tanks. Nato is training Ukrainian personnel. Sophisticated anti-missile and other systems have helped Ukraine put up its stubborn resistance and launch counter-attacks. Step by step, these sorts of moves can be reinforced and extended.

As difficult as it is, the west must end its imports of Russian natural resources, though doing so will damage economies and households. The alternative is to continue to fund Mr Putin’s war machine, prolong the fighting, and help him pay for fresh armaments to attack his next targets. If his ethnonationalism and search for “security” are real, their logical conclusion is a far larger extension of Russia’s “sphere of influence” (ie subjugation), far into eastern Europe and down through the Caucasus towards the Indian Ocean.

With his partnership with China, wary as Beijing must be, President Putin is set on continuing his opportunistic expansionism, driven by his own deranged reading of history.

In some ways, the Third World War has already begun. It is absurd that the west is funding its own mortal enemy.