President Joe Biden on Tuesday said the atrocities committed by Russia in Ukraine amounted to “genocide,” marking the first time he has leveled the accusation against President Vladimir Putin.

“More evidence is coming out about literally the horrible things that the Russians have done in Ukraine,” Biden told reporters during a trip to Iowa. “And we’re going to only learn more and more about the devastation. We’ll let the lawyers decide, internationally, whether or not it qualifies [as genocide] but it sure seems that way to me.”

Biden had stopped short of calling the atrocities in Bucha a genocide as recently as last week, when asked by reporters whether Russian actions there fit that definition. White House national security adviser Jake Sullivan at the time said the killings documented in Ukraine did not rise to the level of “genocide” as defined by the U.S. government.

But in a speech Tuesday bemoaning a spike U.S. gas prices, he referred to the unfolding “genocide half a world away” that he said was committed by a “dictator,” apparently referring to Putin.

Before boarding Air Force One to return to Washington, Biden made clear to reporters that his earlier remarks were directed at Putin.

“I called it genocide because it’s become clearer and clearer that Putin is just trying to wipe out even the idea of being Ukrainian. The evidence is mounting,” Biden told reporters on the tarmac.

Residents of Bucha describe atrocities of Russian troops

In his speech Tuesday, Biden blamed Putin for recent price hikes at the pump. “Your family budget, your ability to fill up your tank, none of it should hinge on whether a dictator declares war and commits genocide half a world away,” he said.

The bodies of 410 civilians were removed from Bucha and other Kyiv suburbs as Russian troops retreated from the area, Ukraine’s prosecutor-general, Iryna Venediktova, said earlier this month. Eyewitnesses in Bucha described what they called arbitrary killings by Russian troops.

The State Department has a lengthy internal process for determining if mass killings amount to genocide, including collecting evidence over a period of time. The U.S. government defines genocide as “an act against members of a national, ethnic, racial or religious group with the intent to destroy, in whole or in part.”

Ukrainian President Volodymyr Zelenskyy, who has called the killings in Bucha a genocide, praised Biden for Tuesday’s remarks.

“True words of a true leader,” he tweeted. “Calling things by their names is essential to stand up to evil. We are grateful for US assistance provided so far and we urgently need more heavy weapons to prevent further Russian atrocities.”

U.N. chief: ‘I will never forget the horrifying images of civilians killed in Bucha’

Zelenskyy has urged the United Nations to take action against Russia, insisting that Moscow’s forces must be held responsible for war crimes and atrocities in Bucha and elsewhere in Ukraine.

United Nations Secretary-General António Guterres referred to “possible war crimes” as he addressed the U.N. Security Council earlier this month.

“I will never forget the horrifying images of civilians killed in Bucha,” he said. “I immediately called for an independent investigation to guarantee effective accountability.”