Ukrainian President Volodymyr Zelensky said the fate of the whole Donbas region hinges on the "very fierce" battle with Russian troops for the flashpoint eastern city of Severodonetsk.
Moscow's forces are concentrating their firepower on the strategically important industrial hub as part of efforts to capture a swathe of eastern Ukraine.
As shelling and air strikes killed another 11 people around the country, Ukraine said on June 9 that the western long-range artillery it has been begging for would end the fight for Severodonetsk in days.
In his evening address to the nation on June 8, Mr. Zelensky said the battle for the city was "very fierce... very difficult. Probably one of the most difficult throughout this war. In many ways, the fate of our Donbas is being decided there."
Following days of raging street battles, Ukrainian officials conceded that Russian troops control a large part of Severodonetsk and that their own forces might have to pull back due to constant shelling.
The cities of Severodonetsk and Lysychansk, which are separated by a river, were the last areas still under Ukrainian control in Lugansk. Lysychansk is still in Ukrainian hands but under fierce Russian bombardment.
After being repelled from Kyiv following their February 24 invasion, Russian President Vladimir Putin's troops have refocused their offensive on the Donbas region, comprising Lugansk and Donetsk.
Part of the Donbas had already been held by pro-Russian separatists since 2014.
At the United Nations, Secretary-General Antonio Guterres added his voice to increasingly dire warnings about the war's impact.
"For people around the world, the war is threatening to unleash an unprecedented wave of hunger and destitution, leaving social and economic chaos in its wake," he said.
Severodonetsk appeared close to being captured just days ago but outgunned Ukrainian forces launched counterattacks and managed to hold out.
Lugansk regional governor Sergiy Gaiday said Western artillery would help secure a Ukrainian victory, echoing Kyiv's repeated calls for more military aid.
"As soon as we have long-range artillery to be able to conduct duels with Russian artillery, our special forces can clean up the city in two to three days," he said.
Mr. Gaiday added that Ukrainian forces in the city remained "highly motivated" and that "everyone is holding their positions", while describing Russian tactics as "very primitive."
The United States and Britain have announced they are providing Kyiv with long-range precision artillery batteries, defying warnings from Mr. Putin.
The Ukrainian presidency said four people were killed and five more wounded in a Russian air strike on Toshkivka, a village around 25 kilometres (14 miles) south of Severodonetsk.
Four more people were killed in fighting in Donetsk, and two were killed by shelling in the north-eastern city of Kharkiv, it said. Another person was killed in the Mykolayiv region in the south.
Russia's defence ministry meanwhile said it had targeted a Ukrainian training centre for "foreign mercenaries" in the Zhytomyr region.
Zhytomyr governor Vitaliy Bunechko confirmed a Russian strike overnight in the town of Novograd-Volynskyi but did not mention a training centre and said he had no information about victims.
The shockwaves from the Ukraine conflict continue to reverberate, especially from a looming global food crisis.
Russia and Turkey made little headway in striking a deal to secure safe passage for grain exports stuck in Ukraine.
At the request of the United Nations, Turkey has offered its services to escort maritime convoys from Ukrainian ports, despite the presence of mines.
"We are ready to do this in cooperation with our Turkish colleagues," Russian Foreign Minister Sergei Lavrov told reporters in Ankara.
Lavrov's Turkish counterpart Mevlut Cavusoglu called Russian demands for an end to sanctions to help grain onto the world market "legitimate".
But Kyiv, which was not represented at the Ankara talks, blamed "Russian aggression, not sanctions" for high grain prices.
Before the war, Ukraine was a major exporter of wheat, corn and sunflower oil.
The situation on the ground in other parts of the Donbas is increasingly desperate.
In the city of Bakhmut, an unoccupied school building was reduced to a smouldering wreck after being shelled Wednesday, with burnt books visible among the rubble, according to AFP journalists. No injuries or deaths were reported.
In Severodonetsk's twin city Lysychansk, residents who had chosen to stay were facing fierce Russian bombardments.
"Every day there are bombings and every day something burns. A house, a flat... And there is nobody to help me," 70-year-old Yuriy Krasnikov told AFP.
"I tried to go to the city authorities, but nobody's there, everyone has run away."
There was some rare good news for Ukraine, as their football side clinched a 1-0 Nations League victory over the Republic of Ireland on June 8.
The victory - thanks to a free kick from Viktor Tsygankov - lifted the country's spirits after their painful failure to qualify for the World Cup.