President Raul Castro on Thursday warned Cuba's future leaders that the US "enemy will never stop being aggressive, dominant and treacherous" on the 50th anniversary of the island's Communist Revolution led by his ailing brother Fidel.
The 77-year-old president also warned of tough challenges ahead, with Cuba hard hit by the global economic crisis and the aftermath of three hurricanes this year that left some $10 billion (Dh36.7bn) in damage.
Despite high hopes for improved relations with Cuba's northern neighbour and decades-long foe after the US election of Barack Obama, Raul Castro warned future leaders against softening toward "the enemy".
"One after the other, all the North American administrations have ceaselessly tried to force regime change in Cuba," Castro said in a speech in Santiago de Cuba, the city where Fidel proclaimed victory over US-backed dictator Fulgencio Batista in 1959 after 25 months of fighting in the Sierra Maestra mountains.
"Resisting has been the pledge and the key of each of our victories during this half-century of tough fighting," said Raul, who officially took over from 82-year-old Fidel last February.
Fidel, who has not appeared in public since undergoing major surgery almost two and a half years ago, sent a brief, signed greeting to the Cuban people in Granma, the Communist Party newspaper.
But his image dominated giant banners and billboards in somber celebrations amid a grim economic outlook.
"The next 50 years... will also be of permanent struggle," Raul Castro said in a 40-minute speech to a crowd of some 3,000 people.
Cuba's Revolution – led by a 32-year-old Fidel Castro and legendary Argentine guerilla Ernesto "Che" Guevara – took on Marxist overtones in May 1961, one month after the attempted invasion of the Bay of Pigs by CIA-backed Cuban exiles.
Then-US president John F Kennedy declared an economic embargo in February 1962, before the Soviet missile crisis that brought the world to the brink of nuclear war.
A White House spokesman Wednesday said Washington "will continue to seek freedom" for the people of Cuba, without elaborating.
But Obama, who takes power January 20, has promised to ease some rules limiting travel by and remittances from Cuban-Americans. Raul Castro has said he is ready for talks with Obama without "carrots or sticks."
The Cuban president has also promised "structural reforms" – a departure from his older brother and leading members of the Communist old guard.
But the global economic crisis may impact the pledged changes, as the president signalled in July when he announced greater government control of revenues and tighter agricultural management.
The Caribbean island still officially operates in the Special Period in Peacetime, an extended economic crisis that began in 1991 after the collapse of its former main benefactor, the Soviet Union.
Life is tough for most of Cuba's 11.2 million people, who earn an average of $20 per month and lean on a parallel economy.
"The Revolution has given us a lot. I'm communist, but I wish there were changes in the economy, that's where the problem is," said Pedro, 65, at Thursday's celebrations.
"The situation is really bad. Salaries are not enough to live off. They've made a lot of mistakes," said Joel Romero, a 41-year-old who gave up his job as a health worker to rear pigs.
Branded US puppets by Havana, Cuban dissidents say there are 219 "political prisoners" on the island.
During his decades in power, Fidel Castro expropriated foreign companies, jailed political enemies and drove well over a million Cubans into exile.
But he also introduced historic reforms, including major education and health care access advances.
The 50-year celebrations coincide with recent moves by Cuba to broaden its international ties. The presidents of China and Russia, Hu Jintao and Dmitry Medvedev, sent congratulatory messages on Thursday.
Leftist Latin American leaders heaped praise on Cuba's past half-century.
Oil-rich Venezuela, Cuba's main business partner, held a special ceremony to commemorate the anniversary.
Venezuelan President Hugo Chavez, also a major US foe, called the Cuban Revolution "the mother of all the revolutions going on in Latin America and the Caribbean."