Today in Cuba, President Obama said, “I have come here to bury the last remnants of the Cold War in The Americas.” During the Cold War, nuclear attacks posed the greatest existential threat to the United States. President Obama’s visit to Cuba marks the end of an era, but today’s terrorist attacks in Brussels remind us we’re in a different one now. We look at the Cold War today as an ancient and sometimes absurd artifact. Yet it represented a very real existential threat to most Americans. Can we compare it to the threat of terrorism we face today?