The scale of the collapse of Russian defences near Kharkiv in north-east Ukraine became clear on Sunday morning after Kyiv launched its largest counter-offensive of the war, seemingly catching Russian forces off guard.
The British Ministry of Defence said on Sunday that Ukraine’s forces had made “significant” gains but that fighting continued around Izyum, a city of 45,000 people that was heavily contested early on in the war, and Kupiansk, a transport hub of rail and road connections that experts say is vital for supplying Russian forces in the Donbas, where fighting has raged since the summer.
"The liberation of settlements in the Kupiansk and Izyum districts of the Kharkiv region is ongoing," the Ukrainian military said in a general battlefield update on Sunday, 200 days into Russia's invasion.
Videos uploaded to social media by conflict tracking organisation Oryx, a website run by military analysts Stijn Mitzer and Joost Oliemans, showed scores of abandoned Russian tanks and artillery pieces in the Kharkiv oblast, indicating the rapid withdrawal of Russian forces.
“Russian forces are not conducting a controlled withdrawal and are hurriedly fleeing south-eastern Kharkiv Oblast to escape encirclement around Izyum,” said the Washington-based Institute for the Study of War, calling the retreat a “rout”.
Military experts said the capture of Kupiansk could spell further setbacks for the Russians.
“Roads, railways, bridges, rivers. How logistics flow in war. Without them, you can’t execute defence, offence, or even controlled retreats,” retired Lt Gen Mark Hertling, former commander of the US Army in Europe, said on Twitter.
The head of the Ukrainian military announced early on Sunday that as much as 3,000 square kilometres had been wrested from Russian control since the counter-offensive was launched at the beginning of this month.
The advances represent the biggest victories for Ukrainian forces since they pushed Russian troops back from Kyiv in the early weeks of the war.
Ukrainian Foreign Minister Dmytro Kuleba used the momentum to appeal to western allies for more stockpiles of sophisticated weapons.
"Weapons, weapons, weapons have been on our agenda since spring. I am grateful to partners who have answered our call: Ukraine's battlefield successes are our shared ones," he said on social media.
"Prompt supplies bring victory and peace closer."
Yet, given the lightning speed of Moscow’s retreat, an unpredictable Kremlin escalation is among the uncertainties.
Russia’s defence ministry on Saturday confirmed the troop withdrawals, yet cast the move as part of a plan to redeploy forces to the eastern Donetsk to “achieve the stated goals of liberating Donbas”.
Outwardly, the Kremlin has shown no signs of panic.
Russian President Vladimir Putin on Saturday kept to his announced schedule, including presiding over the opening of a boxing gym and giant Ferris wheel at a Moscow park. Authorities in the city held a huge fireworks display on Saturday night to mark the city’s founding.
“We should watch for some unexpected reaction from Putin,” Mick Ryan, a retired Australian army general wrote on Twitter. “He (unlike some of his senior military officers) has shown no signs of believing the invasion is in trouble.”
Russian military bloggers and others typically loyal to the Kremlin efforts have started to voice sharp criticism of how Mr Putin’s war – which was meant to overrun Ukraine within days or weeks – had been conducted.
Daniil Bezsonov, first deputy minister of information for the Moscow-backed Donetsk People’s Republic in Donbas, said on Saturday the Russian military had abandoned Izyum and some other localities in Kharkiv.
“Of course, this is the result of high command mistakes,” he said on his Telegram channel.
That downbeat attitude may be permeating through the ranks.
“Russian morale is very low and when morale is low then a shock can lead to disintegration. So this was absolutely on the cards,” Jack Watling, senior research fellow for land warfare at the Royal United Services Institute in London, told Bloomberg News.
“The Russians had too little artillery to compensate for their poor infantry skills.”
The totality of the situation on the ground, and the extent of Moscow’s retreat from the north, remains unclear.
Ukrainian commanders in the field almost certainly have been surprised by the speed and scale with which Russia has folded in Kharkiv, and that also presents dangers, Mr Watling said. “The Russians collapsed and withdrew altogether, and I am sure the Ukrainians were not expecting that.”
Mykola Bielieskov, research fellow at the National Institute for Strategic Studies in Kyiv, said Ukraine’s military will weigh the next steps carefully.
“We still need to consolidate the gains and to clear settlements, to liberate Izyum, ensure the security of the flank from the north, from the Russians in Belgorod,” Mr Bielieskov said.
“So I would say it is better to be conservative and consolidate the gains, because to go further there are risks.”
