Special report: How far will Putin go?

The US and its NATO allies are swiftly warning of retaliation and catastrophic consequences for Russia should President Putin follow through on pledges of nuclear warfare. Many are wondering just how far Putin will push it, as Ukraine continues to bust through Russian lines after weeks of a successful offensive in the east and now the south. The key city of Lyman in Donetsk is now back in the hands of Ukrainian forces. Correspondent Nic Payton Walsh was the first TV journalist to visit the city and he joins the show to discuss.  Also on today's show: US Senate Democrat Jeanne Shaheen, a senior member of both the Foreign Relations and Armed Services committees; former Brazilian Foreign Minister Celso Amorim; Scott Armstrong, author of Adrift: America in 100 Charts. To learn more about how CNN protects listener privacy, visit cnn.com/privacy Learn more about your ad choices. Visit podcastchoices.com/adchoices