What a no-fly zone in Ukraine would mean for the U.S., NATO

There have been growing calls in recent days for the United States and NATO to establish a no-fly zone over Ukraine. Ukrainian President Zelensky reiterated the plea on Monday, but what is a no-fly zone and how would it work? For that we turn to two former U.S. ambassadors to NATO. Retired Army Lt. General Doug Lute and Kurt Volker join Judy Woodruff to discuss.