Cubans marking 50 years of their communist revolution have been warned the next half century will bring just as many problems. The New Year of 1959 saw Fidel Castro’s victory over the dictator Fulgencio Batista. And it was in the same town, Santiago de Cuba, that his brother Raul led the 50th anniversary celebrations.He said Cuba must never relax in the face of threats from the United States: “One after the other, all American governments have tried to bring about regime change in Cuba, using this method or that, with more or less aggression.” The anniversary comes as Fidel Castro’s era is winding down. He is 82, has not seen in public for 18 months and was deemed too ill to attend the celebrations. New President Raul has called for talks with Barack Obama after his inauguration in Washington. The US president-elect favours relaxing some restrictions on Cuba, but says the 46-year trade embargo must stay.