Russia fired its biggest-ever aerial barrage at Ukraine, killing four people and setting government offices in Kyiv ablaze, an attack Ukrainian President Volodymyr Zelenskyy warned would prolong the war.
Zelenskyy said he was counting on a strong United States response shortly after US President Donald Trump indicated to journalists he might be willing to impose more sanctions on Russia.
Russia has intensified its onslaught against Ukraine since a meeting between Trump and President Vladimir Putin on 15 August failed to make any breakthrough on a ceasefire.
After Sunday's attack on Kyiv, flames could be seen rising from the roof of the sprawling government complex that houses Ukraine's ministerial cabinet in the heart of the city — the first time it has been hit during the three-and-a-half-year conflict.
Drone strikes also damaged several high-rise buildings in the Ukrainian capital, according to emergency services.
Russia denies targeting civilians in Ukraine.
It said it struck a plant and a logistics hub in Kyiv, with the Russian defence ministry saying "no strikes were carried out on other targets within the boundaries of Kyiv".
"It is important that there is a broad response from partners to this attack today," said Zelenskyy in his evening address, adding that Putin was "testing the world".
"We are counting on a strong response from America. That is what is needed."
Russia fired at least 810 drones and 13 missiles at Ukraine over the weekend in a new record, according to the Ukrainian air force.
Ukrainian Prime Minister Yulia Svyrydenko posted a video showing a damaged floor in the government building.
"We will restore the buildings," she said. "But we cannot bring back lost lives. The enemy terrorises and kills our people every day throughout the country."
Zelenskyy discussed the attack in a call with French President Emmanuel Macron and said France would help Ukraine strengthen its defence.
At least two people were killed in a strike west of Kyiv, prosecutors said.
The strikes came after more than two dozen European countries pledged to oversee any agreement to end the war, with some saying they were willing to deploy troops on the ground in Ukraine. Source: AP / Evgeniy Maloletka
Among them was a 24-year-old pregnant woman who delivered a premature baby shortly after the attack, with doctors fighting to save her life and that of her baby, state TV Suspilne reported.
Two more died and dozens were wounded in overnight strikes across the east and southeast, authorities said.
Ukraine's foreign ministry highlighted seven horses had also been killed at an equestrian club.
The barrage came after more than two dozen European countries pledged to oversee any agreement to end the war, with some of them stating they were willing to deploy troops on the ground.
Ukraine has insisted on Western-backed security guarantees to prevent future Russian attacks, but Putin has warned any Western troops in Ukraine would be unacceptable and legitimate targets.
Trump has tried to find a way to end the war in recent weeks but has little to show for his efforts.
Russia has continued to claim territory in costly grinding battles and now occupies around 20 per cent of Ukraine.
Tens of thousands have been killed and millions forced from their homes in Europe's bloodiest conflict since World War Two.
