The officials said the soldier from the 4th infantry division was killed on Thursday.
Friday's announcement brings the total number of US soldiers killed to 181 since President George Bush declared an end to major combat.
Earlier in the day, at least two people were wounded, one of them seriously, when three rockets slammed into the main hotel housing foreign journalists and contractors in Baghdad.
Elsewhere, the oil ministry building in the Iraqi capital has also been hit by rocket fire and set ablaze. And a rocket launcher with dozens of rockets was found near the Italian embassy.
Three Katyusha rockets were fired early on Friday at the Palestine Hotel in the centre of Baghdad, Aljazeera's correspondent said.
Rooms on the 8th, 12th, 15th and 16th floors were reportedly damaged and a contractor with the US multinational Halliburton was seriously wounded.
A home-made rocket launcher on a donkey-drawn cart has been found on Saadun Street near the hotel, with rockets on the pavement beside it.
The Sheraton Hotel nearby, also home to many foreign journalists, was evacuated after it also came under fire but there were no reported casualties.
Columns of smoke
The oil ministry building was hit and set ablaze a few minutes after the attack on the Palestine Hotel, Aljazeera's correspondent said.
A US soldier inspects the launcher
used in the morning attacks
"Columns of smoke were rising from the building," he said. "Helicopters then flew low over the area.”
The Iraqi capital has become the scene for almost daily attacks by resistance fighters on US-led occupation forces and targets associated with the government it has installed.
The US has responded by stepping up the intensity of its military operations in and around Baghdad over the past fortnight.
Two makeshift launchers with a total of 52 rockets in their tubes were found near the Italian embassy in Baghdad on Friday shortly after the morning rocket attacks.
The first launcher was found less than 300 metres away, the second some 600 metres away. They were attached to timers but had yet to fire.
Italy's high-profile involvement in the US-led occupation of Iraq has already made it a target for attack. A 12 November bombing of Italy's police base in the southern city of Nasiriya killed 19 Italians and nine Iraqis.
Nicolo Pollari, head of Italy's military intelligence services, said on Tuesday the risk of renewed attacks on Italian interests in Iraq was "very high".