“ The Medal of Freedom may also be awarded to any person, not hereinafter specifically excluded, who, on or after December 7, 1941, has similarly aided any nation engaged with the United States in the prosecution of a war against a common enemy or enemies. The Medal of Freedom shall not be awarded to a citizen of the United States for any act or service performed within the continental limits of the United States or to a member of the armed forces of the United States. ”