U.S. officials believe Russia is laying the groundwork to invade Ukraine. The National Security Council says Russia has positioned a group of operatives to conduct a so-called "false-flag operation" in eastern Ukraine. Meanwhile, a cyberattack knocked out several government websites in Ukraine on Friday. CBS News correspondent Christina Ruffini has the latest, and UCLA political science professor Daniel Treisman talks to CBSN's Lana Zak about why these moves are significant. CBSN is CBS News’ 24/7 digital streaming news service featuring live, anchored coverage available for free across all platforms. Launched in November 2014, the service is a premier destination for breaking news and original storytelling from the deep bench of CBS News correspondents and reporters. CBSN features the top stories of the day as well as deep dives into key issues facing the nation and the world. CBSN has also expanded to launch local news streaming services in major markets across the country. CBSN is currently available on CBSNews.com and the CBS News app across more than 20 platforms, as well as the Paramount+ subscription service. Subscribe to the CBS News YouTube channel: http://youtube.com/cbsnews​ Watch CBSN live: http://cbsn.ws/1PlLpZ7c​ Download the CBS News app: http://cbsn.ws/1Xb1WC8​ Follow CBS News on Instagram: https://www.instagram.com/cbsnews/​ Like CBS News on Facebook: http://facebook.com/cbsnews​ Follow CBS News on Twitter: http://twitter.com/cbsnews​ Subscribe to our newsletters: http://cbsn.ws/1RqHw7T​ Try Paramount+ free: https://bit.ly/2OiW1kZ For video licensing inquiries, contact: [email protected]