Authority of the President to Blockade Cuba
Under international law, the President may institute a blockade of Cuba as an incident to a state of war, and conceivably a blockade could also be justified as a necessary measure of defense.
The legality of the blockade could probably be tested by Cuba, by other countries, and by their nationals in the courts of the United States, and Cuba and other countries could raise the legality issue before the United Nations and the Organization of American States. It is not clear whether this issue could be raised before the International Court of Justice.