WARSAW — Russian President Vladimir Putin and his battered-but-blooded invading forces could prove even more brutal in the next phase of the war in Ukraine following the Russian defeat around Kyiv and the atrocities discovered nearby, U.S. and European officials fear.

“It’s a clear example that they do not consider or do not think about any kind of consequences after the war, you know that actually,” a senior European official from a country said. “For Mr. Putin, it’s the same to have one process in Hague or several processes in Hague.”