White House condemns apparent Ukrainian war crime, says if proven there 'has to be consequences'

• Video released this week appears to show Ukrainian forces executing captured Russian soldiers.
• White House Chief of Staff Ron Klain told CNN there should be consequences for any war crimes.

The White House said Thursday that Kyiv has promised to investigate a video that appears to show Ukrainian forces executing a Russian soldier, saying there should be repercussions for any war crimes.

"I think it's very important that the Ukrainians conduct this war in the accordance with the rules and laws of war," White House Chief of Staff Ron Klain told CNN's Erin Burnett. "They have assured us they are looking into this and that they will impose discipline, their military discipline, if need be on anyone who is responsible."

On Wednesday, video began circulating that showed forces south of Bucha executing at least one Russian soldier, with three other Russian soldiers laying dead beside him. The executioner may have been a part of group of volunteers from neighboring Georgia, per The New York Times.

"It is important for the Ukrainians to fight this war the right way and if this happened there has to be consequences," Klain said.

Under the Geneva Conventions, it is a crime to execute a prisoner of war.

But Klain told CNN the incident, if proven, should not be conflated with the "massive amounts of atrocities we've seen the Russians commit in this war," including the apparent torture and killing of potentially hundreds of civilians in Bucha, north of Kyiv, and the bombing of a maternity hospital in Mariupol.

The "one incident" alleged to be carried out by Ukrainian forces should not "take the focus off the kind of massive atrocities we're seeing the Russians commit," Klain said.