Cuba is a poor, impoverished country which cannot reasonably be considered to be a threat to any other country's national security. They have no military presence to speak of. Moreover, Cuba's proximity to the United States is a serious deterrent from Cuba's threatening of any American ally. Sanctions can't be justified on security grounds.
In my travels, I've never found a more fun loving and hard working people than Cubans. The sanctions that still surround Cuba are no longer appropriate. We are no longer worried about Russian warheads being installed 80 miles away from the mainland US. We are no longer concerned with fighting a never ending war on Communism. The sanctions on Cuba are of a bygone era, and only hurt the Cuban people that could make more from trade, and of course cigar enthusiasts!