A senior U.S. defense official says after weeks of failing to capture Ukraine's capital Kyiv and suffering heavy losses, Russian forces are shifting their ground offensive to the Donbas region in eastern Ukraine. Even as it bombards the country, accusations of Russia committing war crimes are increasing. Imtiaz Tyab reports. "CBS Saturday Morning" co-hosts Jeff Glor, Michelle Miller and Dana Jacobson deliver two hours of original reporting and breaking news, as well as profiles of leading figures in culture and the arts. Watch "CBS Saturday Morning" at 7 a.m. ET on CBS and 8 a.m. ET on the CBS News app. Subscribe to "CBS Mornings" on YouTube: https://www.youtube.com/CBSMornings Watch CBS News live: https://cbsn.ws/1PlLpZ7c​ Download the CBS News app: https://cbsn.ws/1Xb1WC8​ Follow "CBS Mornings" on Instagram: https://bit.ly/3A13OqA Like "CBS Mornings" on Facebook: https://bit.ly/3tpOx00 Follow "CBS Mornings" on Twitter: https://bit.ly/38QQp8B Subscribe to our newsletter: https://cbsn.ws/1RqHw7T​ Try Paramount+ free: https://bit.ly/2OiW1kZ For video licensing inquiries, contact: [email protected]