How should U.S. respond to Moscow's military move in Crimea?

How damaging is Russia’s recent activity in Crimea to Russia’s long-term relationship with the West? Is the current tension adding momentum toward “a new Cold War divide”? Gwen Ifill gets two views from Stephen Cohen of New York University and Michael McFaul, former U.S. ambassador to Russia on the build up to Russia sending troops into Ukraine and how the U.S. should react.