Ukrainian forces are today concentrating on defending Donetsk province in the eastern Donbas after Russia claimed to have taken control of neighbouring Luhansk.
The Ukrainian General Staff said Russian forces were now focusing their efforts on pushing toward the line of Siversk, Fedorivka and Bakhmut in the Donetsk region, about half of which is controlled by Russia.
The Russian army has also intensified its shelling of the key Ukrainian strongholds of Sloviansk and Kramatorsk, deeper in Donetsk.
On Monday, President Vladimir Putin claimed victory in Luhansk province and ordered his forces to continue their offensive in eastern Ukraine, as the five-month long war entered a new phase.
It came a day after Ukrainian forces withdrew from the city of Lysychansk, their last remaining bulwark of resistance in the province.
The battle for the Donbas, the industrialised eastern region of Ukraine, has become the site of the biggest battle in Europe in generations.
'Superhuman effort' needed, says Zelenskyy
Ukrainian President Volodymyr Zelenskyy warned on Monday night that repelling the invader would take time and be hugely challenging.
"We need to break them," he said in his latest evening address. "It is a difficult mission, which requires time and superhuman efforts. But we have no other choice."
Serhiy Haidai, the Ukrainian governor of Luhansk, acknowledged his entire province was now effectively in Russian hands. "We need to win the war, not the battle for Lysychansk ... It hurts a lot, but it's not losing the war," he told Reuters.
He added that Ukrainian forces that retreated from Lysychansk were now holding the line between Bakhmut and Sloviansk, preparing to fend off a further Russian advance.
The UK defence ministry's intelligence assessment on Tuesday said Russia's control of Luhansk allowed Moscow to claim "substantive progress against the policy objective it presented as the immediate purpose of the war, namely ‘liberating’ the Donbas".
But it added: "There is a realistic possibility that Ukrainian forces will now be able to fall back to a more readily defendable, straightened front line."
The battle in the Donetsk area will likely continue with slow advances and "Russia’s massed employment of artillery, levelling towns and cities in the process", the latest bulletin concluded.
Zelenskyy renews appeal for reconstruction aid
President Zelenskyy also used his nightly video address to call for immediate economic aid to help the country rebuild even as fighting continues.
He explained that he needed "colossal funds" to help the population, rebuild the cities and infrastructure destroyed by the war, but also "to prepare schools and universities for a new school year" and "to prepare for winter".
“The restoration of Ukraine is not only about what needs to be done later after our victory, but also about what needs to be done right now. And we must do this together with our partners, with the entire democratic world,” he said.
“A significant part of the economy has been destroyed by hostilities and Russian strikes. Thousands of enterprises do not work. And this means a high need for jobs, to provide social benefits, despite the decrease in tax revenues,” Zelenskyy said.
He had spoken earlier by video conference at the opening of an international conference in Lugano, Switzerland, to prepare the reconstruction of the country. The conference is due to end on Tuesday.
Kyiv has estimated the cost of this project at $750 billion (€718 billion).