Havana ? Fidel Castro was a no-show Saturday at a major military parade that doubled as his 80th birthday celebration, raising questions about whether the ailing leader will ever return to power as his public absence begins taking on a tone of permanence.

Many Cubans had hoped for at least a glimpse of Castro before dozens of olive-camouflaged tanks rumbled through the Plaza of the Revolution and jet fighters soared above the capital to mark the 50th anniversary of the formation of Cuba’s Revolutionary Armed Forces.

Castro hasn’t been seen in public since July 26, before he underwent secretive intestinal surgery and temporarily ceded power to his younger brother, Raul. He delayed his 80th birthday celebration from Aug. 13 to this week in order to give himself time to recover, and speculation had been rife whether he would appear.

The military event, which lasted about two hours, culminated five days of events to celebrate Castro’s birthday – none of which he attended.

Instead, it was Raul Castro, the island’s defense minister, who stood at the mahogany lectern reviewing the troops during Saturday’s parade.

The parade’s most obvious purpose was to warn the U.S. against taking advantage of Fidel Castro’s illness to attack the island. In the last 15 years, the Cuban military has taken on a purely defensive role and is trained to repel invaders.

In a speech that lacked his brother’s rhetorical flourishes, Raul Castro reached out to the U.S. government, which has a decades-old trade and travel embargo against the communist-run island. He did not explain the absence of his brother.

“We take this opportunity to once again state that we are willing to resolve at the negotiating table the long-standing dispute between the United States and Cuba,” as long as the U.S. respects Cuba’s sovereignty, said Raul Castro, who turned 75 in June.

U.S. State Department spokeswoman Janelle Hironimus said Saturday that “the dialogue that needs to take place is one between the Cuban regime and the Cuban people about the democratic future of the island.

“Any deepening of our engagement with Cuba depends on that dialogue and the Cuban regime’s willingness to take concrete steps toward a political opening and a transition to democracy,” she said.

Raul Castro used the event to underscore cohesion among the Cuban people, the armed forces and the Communist Party – a recurring theme among officials in recent days.

Cuban officials insist Fidel Castro is recovering, but U.S. officials say they believe he suffers from some kind of inoperable cancer and will not live through the end of 2007.