U.S. says Russian forces committed war crimes in Ukraine

STORY: At a press briefing, the State Department's recently-confirmed ambassador at large for global criminal justice, Beth Van Schaak, said "we've been shocked by images of Russian forces and strikes hitting civilian sites."

"The United Nations and other credible observers have confirmed hundreds of civilian deaths, and we believe that the exact civilian death toll will be in the thousands," she added.

President Joe Biden last week said Russian President Vladimir Putin "is a war criminal" for attacking Ukraine.

Moscow has yet to capture any of Ukraine's biggest cities following its invasion that began on Feb. 24, the largest assault on a European state since World War Two, raising fears of wider conflict in the West.

Putin calls his offensive a "special military operation" to demilitarize and "denazify" the country. The civilian casualties are thought to be in thousands while the United Nations estimates more than 3.5 million people have fled Ukraine since the beginning of the invasion.