U.S. President Joe Biden said that what happened in the city of Bucha, Kyiv region, indicates that Russian President Vladimir Putin is a war criminal.

"You may remember that I was criticized for calling Putin a war criminal. So, the truth matters - you saw what happened in Bucha. This is evidence that he is a war criminal," the U.S. Embassy in Ukraine quotes Biden's statement on Twitter.

The U.S. President also stressed the importance of gathering information and helping Ukraine.

"We must collect information, we must continue to provide Ukraine with the weapons it needs to continue the fight, and we must get all the details to make it work - to conduct a trial for war crimes," he said.

"This man is cruel. And what is happening in Bucha, screaming atrocities, and everyone saw it," the U.S. president said.