Fidel, who handed the presidency to his younger brother Raul Castro in 2006 due to a health crisis, has laid low in recent months, and his column published in state media was his first since July 3.
In Monday's piece he came out swinging, saying that Obama distorted the situations in Syria, Iran, Iraq, Yemen, Egypt, Afghanistan, North Korea, Libya and the Palestinian conflict, and that the US leader used "a long rant to explain and justify the inexplicable and unjustifiable."
"Who understands the gibberish of the president of the United States before the General Assembly?" Castro asked.
Castro also took issue with the "fascist methods by the United States and its allies to confuse and manipulate global opinion," and said he was heartened by the "resistance" of his key allies Hugo Chavez and Evo Moralez, presidents of Venezuela and Bolivia respectively, who criticized US and UN policy in their speeches.
"Has any nation been excluded from the bloody threats of this illustrious defender of international peace and security?" Castro said of Obama, whose UN quotes he cited extensively in his column.
"Who gave the United States such privileges?" Castro said.
He said countries must consider taking a stand at the General Assembly against the "NATO genocide in Libya," an action Castro described as one of many "flagrant violations of principles."
"Does anyone want it to be recorded that under their direction, the government of their nation supported the monstrous crimes by the United States and its NATO allies?" he said.
Washington and Havana are Cold War adversaries who have brought their mutual dislike and distrust into the 21st century, and Castro routinely makes political attacks on his ideological foe.
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