Cuban leader Fidel Castro has demanded that President Barack Obama return the US naval base at Guantanamo to Cuba without conditions.
Mr Castro, who had recently praised President Obama as "honest" and "noble", also criticised the new US administration for its support of Israel.
"Maintaining a military base in Cuba against the will of the people violates the most elemental principles of international law," Castro wrote in a column posted on the government-run website www.cubadebate.cu.
"Not respecting Cuba's will is an arrogant act and an abuse of immense power against a little country," Castro said, resorting to a charge he has levelled against the 10 previous US presidents since he came to power in a 1959 revolution.
Cuba indefinitely leased Guantanamo to the United States in 1903 after the United States occupied the country during the 1898 Spanish-American War. Castro charges that the base at the south-eastern tip of Cuba was taken over illegally.
Earlier yesterday, Washington's loudest critic in Latin America, Venezuelan President Hugo Chavez, also urged President Obama to return the Guantanamo base, after applauding his decision to close the prison camp for terrorism suspects there.
"Now he should return Guantanamo and Guantanamo Bay to the Cubans because that is Cuban territory," Chavez, Cuba's closest ally, said in a speech in Brazil.
Fidel Castro has been seen only in a few videos and photos since undergoing intestinal surgery in July 2006 from which he never fully recovered.
But he has maintained a public profile through his writings and meetings with visiting foreign leaders, and he is believed to retain an important political role behind the scenes.
His brother Raul Castro provisionally took power after the surgery, then officially became president in February.
Obama has said he wants to move towards normalization of US-Cuba relations but would not eliminate the 46-year-old U.S. trade embargo against the communist-led island without political reforms.
Until Thursday's column, the Castro brothers had praised Mr Obama and held back direct criticism of his administration.
Fidel Castro on Thursday also attacked President Obama for supporting Israel's invasion of Gaza.
"It is the way our friend Obama has fallen into sharing Israel's genocide against Palestinians," Castro wrote in his column called "Deciphering the thought of the new U.S. president."
Reuters