More than 70 Ukrainian soldiers have been killed after Russian troops shelled a military base in Ukraine.
The attack was in Okhtyrka in Ukraine's northeastern Sumy region on Monday, regional governor Dmytro Zhyvytskyy said on Facebook.
Video footage shows the devastation at the scene, with piles of rubble, a burnt out building and car.
Russia faces increasing isolation over its invasion of Ukraine, with fierce resistance on the ground denying President Vladimir Putin decisive early gains despite heavy shelling and a huge military convoy outside the capital, Kyiv.
"Barbaric rocket attacks and MLRS (multiple launch rocket systems) of peaceful cities are evidence that they are no longer able to fight armed Ukrainians," Ukrainian Defence Minister Oleksii Reznikov said on Facebook.
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Ceasefire talks between Russia and its southern neighbour held on Monday failed to reach a breakthrough and negotiators have not said when a new round would take place.
"What I think is pretty certain is Russia is off their timeline. I think they thought that within 72 hours they'd hold Kyiv," US Republican Senator Marco Rubio said after a classified briefing with top Biden administration officials.
But fighting on several fronts was taking a toll.
More than 500,000 people have fled Ukraine, according to the United Nations refugee agency, setting off a refugee crisis as thousands await passage at European border crossings.
Public health experts say Ukraine is running low on critical medical supplies and fears of a wider public health crisis are growing as people flee their homes and health services and supplies are interrupted.
Washington has ruled out sending troops to fight Russia or enforcing a no-fly zone as requested by Ukraine, fearing an escalation between the world's top two nuclear powers.
But, the United States and its allies have instead promised military aid to Kyiv, as President Volodymyr Zelenskiy warned the capital was under constant threat.
A stream of companies pulling out of Russia is expected to grow today.
Oil companies Shell, BP and Norway's Equinor have said they would exit positions in Russia, which relies on oil and gas for export earnings.
