Serhiy Hayday, the exiled Ukrainian head of the Luhansk region, said on Tuesday that fierce battles were under way in Lyman, a town east of Izyum, a major military command post from which Russian forces fled days earlier. The region — stretching from Izyum to northern parts of the Luhansk region — had been used by Russia for months as a staging area for its push to capture the last corner of Donbas not yet under its control. If Kyiv retakes the area, it would make it all but impossible for Russia to encircle Ukrainian forces in the region. “We are monitoring the situation in Lyman — the liberation of which is key for our region, fighting is still going on around the city,” Hayday said in a Telegram post on Tuesday. You are seeing a snapshot of an interactive graphic. This is most likely due to being offline or JavaScript being disabled in your browser. Ukrainian soldiers on Monday posted photographs of themselves in the nearby town of Svyatohirsk, claiming they had fully recaptured it. Ukrainian military officials have said in recent days that they have taken more than 3,000 sq km of terrain in what has become Moscow’s biggest military setback since it was forced to scrap plans to conquer Kyiv. But late on Monday night President Volodymyr Zelenskyy practically doubled those claims as Ukraine’s forces continued to advance. “From the beginning of September through today, our soldiers have already liberated more than 6,000 sq km of Ukrainian territory — in the east and south,” he said. “The movement of our troops continues.” Serhiy Kuzan, a defence ministry adviser, said that after capturing Izyum and Kupyansk, the railway hub to its north, Ukrainian forces could sever a major supply line for Russian forces in the Luhansk towns of Severodonetsk and Lysychansk. The capture of both towns — then the last Ukrainian-controlled cities in Luhansk — in the summer was a major symbolic victory for Moscow after months of grinding artillery battles. Hayday suggested Russian troops had also already started leaving the town of Kreminna, 25km north of Severodonetsk, but cautioned that they had returned to the town of Svatove, which is further to the north, after initially fleeing. You are seeing a snapshot of an interactive graphic. This is most likely due to being offline or JavaScript being disabled in your browser. Some western officials have been emboldened by Ukraine’s progress, saying that recent advances have bolstered the case for Nato countries and partners to provide Kyiv with lethal aid. A senior US defence official said Washington and its allies were discussing Ukraine’s longer-term needs, such as air defences, and whether it might be appropriate to give Kyiv fighter aircraft in the “medium to longer term”. To date, the US and its allies have declined to do so. Karine Jean-Pierre, White House press secretary, said the US and its allies had “worked to fulfil the Ukraine request for what they need to be successful on the battlefield — and that’s what we’re going to continue to do”.

The US has already allocated much of the $40bn aid package for Ukraine that President Joe Biden signed into law in May, a package that was meant to last until the end of September. Biden has asked Congress for about $13bn more in assistance for the country, including lethal aid, and Washington is expected to announce another weapons package in the coming days. But Washington considers that Ukraine still faces a tough fight, despite the success of its offensive around Kharkiv, the country’s second city, which one official said had impelled a Russian retreat north and east and, in some cases, back across the border. US secretary of state Antony Blinken said that, while Ukrainian forces had made “significant progress” in their counteroffensive, particularly in the north-east, it was “too early to tell exactly where this is going”. “The Russians maintain very significant forces in Ukraine, as well as equipment and arms and munitions,” he added. “They continue to use it indiscriminately against not just the Ukrainian armed forces but civilians and civilian infrastructure.” The Russian defence ministry has acknowledged its troops have pulled back in the Kharkiv region, but authorities have avoided calling it a retreat. The Kremlin said on Monday it would press on with its invasion of Ukraine “until all the goals that were originally set are achieved”.