President Biden said he believes Russian President Putin is "a war criminal" during a briefing on humanitarian efforts to aid Ukraine. NBC's Kelly O'Donnell reports from Poland. » Subscribe to MSNBC: http://on.msnbc.com/SubscribeTomsnbc About: MSNBC is the premier destination for in-depth analysis of daily headlines, insightful political commentary and informed perspectives. Reaching more than 95 million households worldwide, MSNBC offers a full schedule of live news coverage, political opinions and award-winning documentary programming -- 24 hours a day, 7 days a week. Connect with MSNBC Online Visit msnbc.com: http://on.msnbc.com/Readmsnbc Subscribe to MSNBC Newsletter: MSNBC.com/NewslettersYouTube Find MSNBC on Facebook: http://on.msnbc.com/Likemsnbc Follow MSNBC on Twitter: http://on.msnbc.com/Followmsnbc Follow MSNBC on Instagram: http://on.msnbc.com/Instamsnbc Biden Calls Putin 'A War Criminal' During Humanitarian Response Briefing In Poland