Cuba's communist government said it would defend itself against any U.S. attempt to take advantage of Fidel Castro's health crisis as some exiles urged Washington to go further in fostering a democratic transition on the island. "The people know they have a resource, a weapon, a place to defend the revolution if necessary," Rogelio Polanco, editor of the Communist youth newspaper Juventud Rebelde, said on state television Thursday evening."Once again, they shouldn't make a mistake, not to fantasize ... thinking their desires are reality," Polanco said in a public affairs program discussing how exiles celebrated Castro's recent surgery for intestinal bleeding. "They should not mess up and commit the greatest error of all time."