Castro warned Cuban ambassadors that he believed there existed "grave danger" of a US and Israeli "aggression" against Iran or North Korea.
"All responses have already been programmed," warned the 83-year-old leader of the Cuban revolution. "It's only a question of seconds ... Today it is not possible to draw plans that would not be computerized."
Speaking of his health, Castro said that he was able "to partly repulse his consistent and grave health situation," but did not elaborate.
The address was Castro's fifth public appearance in only nine days.
Castro appeared on state-run television for the first time in nearly a year last Monday, looking alert and healthy but with a wavering voice that betrayed his advanced age.
The Cuban revolutionary has made only sporadic appearances -- either on television or in public -- since emergency intestinal surgery in July 2006 drove him to hand power to his younger brother Raul.
The bout of Castro appearances comes at a delicate time politically for Cuba as it begins releasing dissidents under a landmark deal brokered with the Catholic Church last week.
If all 52 activists are freed as the government has promised, it would be the largest prisoner release of Raul Castro's tenure.
Castro and a band of followers launched their revolt in earnest on December 2, 1956 when they landed in southeastern Cuba on the ship Granma.
Twenty-five months later, against great odds, they ousted president Fulgencio Batista and Castro was named prime minister.
After leading the Americas' only one-party communist country through nearly half of the 20th century and into the 21st, he still serves as first secretary of Cuba's Communist Party.
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