President Biden's visit to Poland Friday spotlights that country's importance to the military and humanitarian effort in Ukraine. Since the start of the invasion of Ukraine no nation has become more important to western efforts to repel Russia. Stephen Mull, former U.S. ambassador to Poland and now the vice provost for global affairs at the University of Virginia, joins Nick Schifrin to discuss. Stream your PBS favorites with the PBS app: https://to.pbs.org/2Jb8twG Find more from PBS NewsHour at https://www.pbs.org/newshour Subscribe to our YouTube channel: https://bit.ly/2HfsCD6 Follow us: Facebook: http://www.pbs.org/newshour Twitter: http://www.twitter.com/newshour Instagram: http://www.instagram.com/newshour Subscribe: PBS NewsHour podcasts: https://www.pbs.org/newshour/podcasts Newsletters: https://www.pbs.org/newshour/subscribe