The Guardian view on Ukraine’s counteroffensive: a stunning breakthrough

The burnt-out tanks, abandoned crates of ammunition and other evidence of swift, chaotic Russian flight tell their own dramatic story. The stunning, lightning offensive by Ukrainian troops in the north-east of the country constitutes the most significant moment in the war since March, when Vladimir Putin’s assault on Kyiv was repulsed and his invading forces beat a hasty retreat eastwards.

Over five days, thousands of square kilometres of the occupied east, including the strategically vital cities of Kupiansk and Izium, have been liberated. According to Ukrainian commanders, Russian troops have been pushed back to the border. The Institute for the Study of War estimates that the counteroffensive has taken control of more territory than Russian forces have managed in all operations since April. Skilful use of western rockets and artillery allowed the Ukrainian military to successfully target Russian supply lines and erode its massive advantage in military hardware. Already low in morale – and lacking elite combat troops who had been dispatched to deal with a prior offensive in the south – Russian fighters abandoned overnight territory that had been won after weeks of attritional warfare.

It would be rash to underestimate the possible ferocity of Moscow’s response. Subsequent Russian missile attacks on the power grid in Kharkiv suggest that the Kremlin may be plotting the most brutal of energy wars this winter, depriving Ukrainians of heat and light. That is a dire prospect, and such targeting of civilian infrastructure provides yet more evidence of the criminal ruthlessness of Mr Putin. Fighting during the coming weeks is certain to continue to ebb and flow. But the north-eastern offensive has given Ukrainian forces invaluable momentum for the vital period before the winter freezes the conflict, and put stretched Russian lines on the back foot.

Mr Putin’s plan B, following the humiliating debacle of his own blitzkrieg on Kyiv, was to consolidate and expand Russia’s grip on Ukraine’s east. Incremental progress backed by relentless use of heavy artillery already appeared to have stalled in a summer stalemate. The shambolic Russian retreat of recent days has now led to a growing drumbeat of disquiet on popular ultra-nationalist blogs and will further damage morale on the ground. While not yet unpopular, it is becoming hard for even practised media propagandists to present Mr Putin’s “military operation” as a success.

For Volodymyr Zelenskiy, the gains in the north-east will be a priceless lobbying asset as he seeks to persuade western allies to step up delivery of the advanced weaponry used so effectively by his commanders. The successful counteroffensive – and smaller gains in the south – has undermined the idea that Russian consolidation in those regions is inevitable. The strength and determination of Ukrainian resistance will be redoubled, and it will become harder for Russia to establish its authority in recently occupied eastern territory. Ultimately, driving Russian forces back to at least within the territories taken over in 2014 no longer seems implausible. But first there will be the grimmest of winters to endure. This could lead to another exodus of refugees, at a time when domestic economic hardship is stretching goodwill among European populations. The most significant achievement of a stunning string of victories may be to encourage western nations to stay the course in a war that is a long way from reaching any kind of conclusion.