Biden calls Putin a 'murderous dictator'

 He also said the Russian leader is "a pure thug who is waging an immoral war against the people of Ukraine."

Russia's war in Ukraine entered its fourth week Thursday with civilian areas battered from the air, Moscow's military offensive stalled on the ground and little sign of an imminent end to the conflict or the humanitarian crisis it has fueled. 

Ukraine accused Russian forces of bombing a theater in besieged Mariupol that was sheltering hundreds of people and, according to satellite images from the U.S. government-linked technology firm Maxar, appeared to have the word "CHILDREN" written outside the building in huge white letters. 

"The building was fully damaged, but the shelter fortunately withstood. It did not turn into one of more mass graves," Ukraine's representative to the United Nations, Sergiy Kyslytsya, said Thursday. 

Also Thursday, it was confirmed by the U.S. that an American citizen was killed in Ukraine. A Minnesota family said that Jim Hill of Idaho was killed in Chernihiv. 

Russia's bombardment of its democratic neighbor has already forced more than 3 million people to flee and stoked an intense global backlash. President Joe Biden labeled Russian President Vladimir Putin "a war criminal" on Wednesday, and matched his rhetoric with a promise of fresh military support for Kyiv after its leader pleaded with the United States and its allies to do more to help his country defend itself against the Russian onslaught.