Cuba marched against the US blockade and sanctions. Photo: Enrique González (Enro)/ Cubadebate.In the stillness of a Havana night, the only sounds are the hum of a generator at a distant hospital and the murmur of a family gathered by candlelight. For them, “US national security” is not an abstract concept debated on American cable news; it is the tangible reality of a 20-hour blackout, the smell of spoiled food, and the fear for a child’s refrigerated medicine. This is the face of a policy that the United States government characterizes as a response to an “extraordinary threat.” The real threat, however, is not military. It is the 67-year-old defiance of a small island nation that has refused to relinquish its sovereignty.