VANESSA ARRINGTON
Associated Press

HAVANA - Cubans awoke to air raid sirens Sunday and practiced shooting, putting on gas masks and doing duck-and-cover drills as the communist nation wrapped up a week of preparation after Fidel Castro's government has warned against possible attacks from the United States.

The activities, called the Strategic Bastion 2004 Exercise, were intended as an evaluation of how prepared Cuba is to face military attack during President Bush's second term.

State-run newspapers reported Sunday that the exercises were a success and that Cuba's "capacity to resist and overcome an imperialist aggression" was demonstrated.

Since even before the United States launched its unilateral attack on Iraq last year, Cuba has insisted that a similar U.S. strike is possible.

"The risks of (U.S.) aggression are real," President Fidel Castro said Sunday on Cuban television.

American authorities have repeatedly rejected that idea, saying there are no plans to attack Cuba. Last week, the U.S. State Department said the large-scale exercises in Cuba were held to distract people from the hardships of their lives.

Cuban army troops, reserves and militia spent the week firing rockets, launching grenades and practicing drills with civilians. Soldiers put up barricades in Havana neighborhoods as fighter jets flew overhead.

Thousands of Cubans took to the streets, taking their prearranged places under the doctrine of "The Peoples' War," in which every citizen, young and old, participates in the defense of the country.

Children were sent to schools early Sunday to practice duck-and-cover drills. Civilians practiced shooting, conducted first aid and gas masks drills.

Work groups gathered to discuss how to guarantee food, water and health care for the population in the event of an attack, as well as to plan evacuations, arrange security and set up a system for communicating with civilians.

State media reported that a total of four million Cubans participated in the drills, the biggest of their kind in 18 years.

Cubans from defense organizations that include much of the general population participated as did defense forces of the Interior Ministry, which oversees internal security.

Defense Minister Raul Castro, who oversaw the operation, toured several sites to motivate participants.

"There are Cubans of every color, making up a precious rainbow, but all have the same language, purpose, ideal: that unity is our most powerful weapon," Castro told civilians in Havana, according to Sunday's edition of Juventud Rebelde, the Communist Party's youth newspaper.