Inside Europe: Tensions escalate between Russia and Ukraine

Tensions between Russia and Ukraine have escalated sharply following a military crisis off the Crimean Peninsula. Ukrainian President Petro Poroshenko warned his country was at threat of a full-scale war with Russia. Keith Walker speaks with DW's Kyiv reporter David Stern and asks him if this is the most dangerous situation we've seen in this conflict since Russia annexed Crimea back in 2014.