Still, it is all in the family. The forces are headed by Mr Castro's younger brother Raul, 63, and it is highly unlikely, if not impossible, that the army's and Raul's increasing prominence go against big brother's will.
As the party increasingly goes the way of its illustrious East European ancestors, the Revolutionary Armed Forces (FAR) of Cuba have staged a kind of creeping coup, according to dissidents and diplomats here. With the Cold War over, the army has turned its gaze from the old enemy across the Florida Strait and declared war on foes closer to home: dissidence and the collapsing economy. "For the last couple of years, the armed forces have realised that the main threat is no longer a US invasion. The principal threat is the economy," a West European diplomat here said.
As a result, and partly because the Soviet Union's collapse has left them without moral and technical support, the new enemies have been taken on with a vengeance. "As dissidence, or let's call it outrage, disgust and anger grows, the army is increasingly being called in to keep the lid on," said one local dissident. "They're reported to run more than 40 jails holding more than 50,000 prisoners.''
Perhaps more significantly, FAR has become probably the biggest individual business enterprise, running agricultural farms, construction companies, messenger services, electronic equipment factories, foreign currency shops and a fast- expanding tourism concern called Gaviota (Seagull).
Diplomats estimate the armed forces generate about $200m (pounds 129m) a year, almost a sixth of the island's entire foreign currency income. "There has certainly been a change of role," said one longtime Western diplomat . "And Raul is leading the charge.
"He's now got a very high profile, appearing at least two or three times a week in the media, about as much as Fidel himself. He's presented as the one who gets people to work together. He's not the tall, handsome, brave icon. He's the likeable, bold, shrewd organiser, a very different model from Fidel.''
Diplomats are agreed that Raul's increasing prominence, and his brother's low profile, do not point to a power push by the younger brother. More likely, they say, they are pieces in Fidel's master plan for retaining power beyond the grave, and a way of putting the 160,000-strong army to good use.
Raul Castro first hinted at the army's new role a year ago when, in a speech given prominence by all the official media, he said "beans are more important than guns".
Army units, stood down from awaiting the Yankee invaders, had already become self- sufficient in food by running their own farms. Last September, in the face of harsh rationing and desperate shortages, they opened "agro-markets" in Havana and elsewhere to sell off excess produce.
Although prices are relatively high compared with subsidised, but often near-empty rationing shops, the markets give Cubans with decent salaries access to meat, fresh food and vegetables.
Adding to the armed forces' income - they now create almost a third of their budget - is the expanding Gaviota tourism group and popular TRD shops, which sell clothes, alcohol, cigarettes, food and toilet goods not available elsewhere. In a word-play on the acronym TRD, Cubans call them "Shops for ripping off our hard currency''.
Gaviota, which began by providing holidays for Cuban and Soviet military personnel, now owns some of the best hotels and runs its own airline, Aerogaviota, using air force pilots - who used to fly MiG fighters to watch out for Yankees - to ferry tourists around the country and to the Cayman islands.
''The armed forces have clearly changed their strategy from preparing for a head-on invasion," the West European diplomat said. "While concentrating personnel on the economy, they have also moved their military strategy to a more guerrilla-based idea, based on sabotage.
"They've built tunnels all around Cuba, which would act as shelters and as bases. The idea would be to withstand bombardment, then, if ground forces came, emerge from the tunnels to pick them off.''