STORY: U.S. President Joe Biden on Monday accused Russian President Vladimir Putin of war crimes and called for a trial, adding to the global outcry over civilian killings in the Ukrainian town of Bucha as more graphic images of their deaths emerged.
"This guy is brutal. And what's happening in Bucha is outrageous, and everyone's seen it."
Footage and photographs showed mass graves, and bodies of civilians lying in the street, next to toppled bicycles or grocery bags... some with their hands tied and gunshot wounds to the head, after Ukrainian forces seized the town back from Russian troops.
"We have to gather the information. We have to continue to provide Ukraine with the weapons they need to continue the fight. And we have to get all the details so this can be an actual, have a war crimes trial."
Ukrainian President Volodymyr Zelenskiy said on Monday while touring the devastation in Bucha that the deaths constituted genocide by Russian troops.
"You are here today and can see what happened. We know of thousands of people killed and tortured, with severed limbs, raped women, murdered children. I think it is more than… This is a genocide.”
The Kremlin denied any accusations of murdering civilians, and said the graves and corpses in Bucha had been staged.
Before Bucha, Ukraine and its Western allies accused Russian forces of targeting civilians, citing the bombing of a maternity hospital in Mariupol and a theater marked as sheltering children.
The International Criminal Court has already begun an investigation.
Rebecca Hamilton, Associate professor of law at American University Washington College of Law, says while it can take years to bring a defendant to trial for war crimes, it is a worthwhile pursuit.
"The people who are victims and survivors of the crimes that we are seeing deserve justice. And as an international community and these prosecutions would take place in an international forum, it sends a strong, expressive signal that these kinds of activities are not acceptable."
U.S. defense officials said the Pentagon could not independently confirm the atrocities.
Biden previously called Putin a war criminal following Moscow's Feb. 24 invasion of its neighbor - words the Kremlin has said further damaged U.S.-Russian ties.