Updated

Cuban officials said Saturday that Fidel Castro was steadily recovering from surgery and the government was still preparing for its worst-case scenario: an attack by government opponents taking advantage of the leader's health crisis.

Castro, whose 80th birthday is Aug. 13, has made no appearances in the five days since his surgery for gastrointestinal bleeding was announced to the Cuban public. Defense Minister Raul Castro, his younger brother and the man named to temporarily replace him as the island's top leader, also was nowhere to be seen.

Vice President Carlos Lage said that Fidel Castro is recovering satisfactorily from surgery and that the communist leader sent his "fraternal greetings" to the people of Bolivia, according to Cuban news agency Prensa Latina. Lage was in the South American nation for the Sunday opening of a convention to rewrite its constitution.

CountryWatch: Cuba

Lage is among a group of six Cuban leaders assigned leadership responsibilities by Fidel Castro after the leader's surgery. He is charged with overseeing Castro's "energy revolution," a massive renovation of the island's antiquated electrical grid.

Cubans had been warned there would be few details about the leader's health — called "a state secret" in a Tuesday statement attributed to Castro. Yet some privately speculated the lack of information could indicate he was extremely ill.

The Cuban government beefed up security, mobilizing citizen defense militias and asking military reservists to check in daily because of the concerns. Veterans — most of them in their 60s and 70s — promised they would fight for Cuba in the event of an attack.

"We will continue working with the same revolutionary fervor that you taught us," the Association of Combatants of the Cuban Revolution said in a statement on the Communist Party daily Granma's front page. The veterans fought in Castro's battles of the 1950s to oust dictator Fulgencio Batista and then defended the island against the failed U.S.-backed Bay of Pigs invasion.

The current efforts appear designed as much to bolster internal solidarity as to quell an outside threat.

Granma ran a series of emotional front-page statements by some of the island's top cultural figures, wishing Castro a steady recovery and pledging loyalty to Castro and the socialist system he created.

"This is a delicate moment and it's necessary to prepare, because the enemy might have illusions," Juan Formell, the director of Los Van Van, one of the island's most popular musical groups, said from Japan. "I trust in our Armed Forces, and in our people."

Folk singer Pablo Milanes, also traveling outside Cuba, said he promised to represent Castro and the Cuban people "as this moment deserves: with unity and courage in the presence of any threat or provocation."

The enemy in Cuba is perceived to be the U.S. government and hardline Cuban-American exiles. President Bush's call on Thursday for democratic change on the island was seen as a provocation, as are statements like those made this week by William Sanchez, an attorney for the Cuban-American nonprofit Democracy Movement who urged Bush to tell Cuba to set an elections timetable and let Cuban-Americans come to the island to help with a political transition.

The U.S. government insists it is pushing for peaceful change in Cuba and has no intentions of invading. White House press secretary Tony Snow dismissed as "absurd" the suggestion that the United States would attack.

In Guatemala, Cuban Health Minister Jose Ramon Balaguer told Radio Sonora Friday that Castro "underwent surgery from which he is recovering satisfactorily." Balaguer is another longtime Communist Party leader, and a physician, named by Castro to watch over his pet health projects.

Parliament Speaker Ricardo Alarcon said in comments broadcast Saturday by CNN en Espanol that Castro "remains in stable condition" and "is resting in order to recover as quickly as possible." The interview was taped late Thursday by state-run Cubavision Internacional in a special package for CNN and was not previously aired.