With Russian forces strengthening their grip on the Crimean Peninsula and Russian President Vladimir Putin apparently unconcerned by threats of sanctions from the West, many observers fear further escalation. Germany has described the Russian takeover of Crimea as the worst crisis in Europe since the fall of the Berlin Wall. So what happens next, and what should the response be from the United States? Ivo Daalder helps us answer that question. Daalder is president of the Chicago Council on Global Affairs and was the U.S. ambassador to NATO from 2009 to 2013.