State radio described the mood of the parade as somber, a reflection of the delicateness of military issues in the new center-left government, whose coalition partners, including Communists, vigorously opposed the war.
Fausto Bertinotti, who leads a Communist party in Premier Romano Prodi's new center-left government, described his presence at the military parade as part of his obligations as president of the Chamber of Deputies.
"If it were up to me, I would dress the parade in the colors of peace," Bertinotti said as he left the parade, referring to the rainbow colors which have come to express anti-war sentiment in Italy. News reports said Bertinotti wore a peace-flag pin on his lapel.
The parade, which passed by the ancient Roman forums, with the Colosseum in the background, was a showcase of Italian military, police and fire units. Air force jets screeched in the skies, emitting trails of smoke in the red, white and green colors of the Italian flag.
Prodi, flanked by his defense minister, were among the VIPs in the reviewing stands.
The parade's ending point, Piazza Venezia, the city's central square, was a few blocks away from the end of an anti-war parade of protesters who marched behind a large flag in the colors of the rainbow.
In Venice, ANSA reported that police dragged away some anti-globalization protesters, including their leader Luca Casarini, from St. Mark's Square after demonstrators hung a peace flag from a flag pole and chanted anti-war slogans with a megaphone, the AP reports.
In Bologna, about a hundred anti-war protesters held a noisy rally, banging pots and pans and blowing whistles, ANSA said. At one point, demonstrators hurled tomatoes, one of which hit a local policewoman, the report said.
Rainbow flags still hang from many windowsills and balconies throughout Italy, a sign of widespread disagreement by Italians with former conservative Premier Silvio Berlusconi's support for the Iraq war.