US President Joe Biden called Russian President Vladimir Putin a war criminal and stated he would call for a war crimes trial. "You have seen what happened in Bucha. Putin is a war criminal" he said. 

Biden also stressed he would seek more sanctions following the reported atrocities in Ukraine, but his comments to reporters did not go so far as to call the actions genocidal. 

"We must continue to provide Ukraine with the weapons it needs to continue the war. And we have to gather all the details in order for that to be true - to have a war crimes trial," Biden was quoted as saying by the Associated Press. 

"What is happening in Bucha is wild and everyone sees it," Biden added. 

In a separate move, a senior US defence official said that the US believes Russia has repositioned about two-thirds of its forces from the Kiev district, with many of them consolidated in Belarus. They predict they will be redirected to eastern Ukraine, but this has not yet been confirmed.