Solemn music played and mourners applauded as the body of Calipari was brought into the church in Rome for the start of the funeral service.
Calipari, 50, leaves behind a wife and two children, 13 and 19.
The honors shown Calipari reflect the status of national hero that Italy has accorded him since his shooting death on 4 March.
Calipari was killed as he reportedly shielded Italian journalist Guiliana Sgrena from fire from U.S. forces in Baghdad. He was the senior member of a team of secret-service agents that had picked up Sgrena in a prearranged meeting with her captors. The team was taking Sgrena by car to the airport to be flown to freedom.
The details of the shooting -- in which Sgrena and two other agents were also wounded -- are a matter of dispute.
The U.S. military has said the Italians’ car came under fire because it was speeding toward a checkpoint and ignored signals to slow down. U.S. forces say they first fired warning shots into the car’s engine block before firing into the car itself.
White House adviser Dan Bartlett called the shooting “a horrific accident, on which President [George W.] Bush called Prime Minister [Silvio] Berlusconi to offer his condolences, as well as to make sure that there is a full investigation.”
But Sgrena has contradicted the U.S. account. She said the car was not traveling at high speed and was not near a checkpoint when it came under fire.
"There was no checkpoint, and we were going at a normal speed. We were going about 50-60 kilometers an hour -- which for a place like this was completely normal. We were not traveling along the normal road for the airport; we were traveling on a privileged road that is less dangerous than the normal one, where every day bombs explode," Sgrene said.
Sgrena, a war correspondent for the Italian communist daily “Il Manifesto,” has suggested that the shooting might have been deliberate.
She told Sky Italia news channel yesterday that “everyone knows the Americans don’t want hostages to be freed by negotiations, and for that reason, I don’t see why I should rule out that I was their target.”
The death of Calipari could further stoke antiwar sentiment in Italy, where majority public opinion opposes the U.S.-led invasion of Iraq.
Antiwar sentiment has already escalated in Italy in the past month due to the abduction of Sgrena, an award-winning reporter in her mid-fifties. She was taken captive on 4 February on a Baghdad street in what many Italians regard as proof that the U.S. invasion has brought lawlessness -- not opportunities -- to Iraq.
Prime Minister Berlusconi has defied Italy’s antiwar movement to maintain some 3,000 Italian troops in Iraq – making his government one of Washington’s staunchest allies there.
Italy’s center-left parties hope to unseat Berlusconi in elections next year and already are campaigning on a platform of withdrawing Italian soldiers from Iraq.
Some observers predict the killing of Calipari could grow into a major test of U.S.-Italian relations despite the two governments’ cooperation in Iraq.
Italy’s mainstream daily “La Stampa” said in a front-page editorial yesterday that “the incident could have serious political consequences.”
Italy and the United States discovered once that U.S. responsibility for Italian deaths can severely test relations.
Emotions still run high in Italy over the deaths of 20 people when a U.S. Marine jet strayed from its permitted altitude and sliced through a gondola's cables in the Italian Alps in 1998.
The pilot was later sentenced by a U.S. military court to six months in prison and dismissed from the Marines over the destruction of a flight recording that might have incriminated him. Many Italians considered the punishment inadequate.