The press secretary for the Kremlin has said that Russia would not rule out the possibility of taking "full control" of Ukrainian cities if necessary.
Bombing and attacks have continued in the war-torn region for a 19th day, with at least one person killed in a strike on a block of flats in the capital Kyiv.
Other attacks in Donetsk, Mariupol and Dnipro are continuing.
And things could get worse if the situation continues, a Russian government official has said.
Speaking on Russian news channel Rossiya 24 TV, Dmitry Peskov, the press secretary for Vladimir Putin, said: "Warfare will inevitably lead to a large number of casualties among civilians.
"The ministry of defence, while ensuring maximum safety of the peaceful population, does not rule out the possibility of placing under its full control major population centres... with the exception of zones used for humanitarian evacuations."
Mr Peskov also claimed the EU were "pushing Russia towards storming major cities in Ukraine with a view to place responsibility for civilian deaths on our country".
"We think that such a position is provocative," he added.
The comments come after a major missile attack on a military facility in western Ukraine just 10km away from the Polish border.
Poland is a member of NATO.
At least 35 people are known to have been killed and more than 130 suffered injuries so far, according to officials in Yavoriv.
They said that up to 30 missiles were fired at the International Center for Peacekeeping and Security on Sunday morning.
