President Joe Biden on Wednesday called Russian President Vladimir Putin a war criminal as the atrocities in Ukraine mount and the president there begged the U.S. Congress for more help.

“He’s a war criminal,” the president said of Putin as he left an unrelated event. It’s the sharpest condemnation yet of Putin and Russian actions by a U.S. official since the invasion of Ukraine.

While other world leaders have used the words, the White House had been hesitant to declare Putin’s actions those of a war criminal, saying it was a legal term that required research.

But in a speech Wednesday, Biden said Russian troops had bombed hospitals and held doctors hostage. He pledged more aid to help Ukraine fight Russia.

(By AP writer Lisa Mascaro)