The United States and Italy say they disagree on the conclusions from a joint investigation into the killing of an Italian agent in Iraq by US troops.
Nicola Calipari's death was mourned across Italy
Nicola Calipari died trying to protect a freed Italian hostage - journalist Giuliana Sgrena - as their car came under US fire near Baghdad airport.
US investigators are reported to have found the soldiers "not culpable".
Observers say the outcome is likely to intensify pressure on Italy's leaders to pull troops out of Iraq.
Prime Minister Silvio Berlusconi has always been one of President George W Bush's most steadfast supporters on Iraq, but the war has been thoroughly unpopular with most Italians, says the BBC's Mark Duff.
The joint US-Italian statement said the countries remained strong allies despite the shooting.
But the discord threatens to add a foreign gloss to Mr Berlusconi's ever-lengthening list of domestic political woes, our correspondent says.
The investigation's findings were not disclosed in the statement - but Rome and Washington have differed over what led to the incident on 4 March.
US military: Car approaches checkpoint at high speed
Troops attempt to tell driver to stop with arm signals, lights and warning shots
Soldiers shoot into engine
Italian government: Italy makes all necessary contacts with the US for safe passage
The driver stops immediately when a light flashes 10m away
At the same time, shots are fired into car for 10-15 seconds
The joint statement released on Friday said: "Investigators did not arrive at shared final conclusions even though, after examining jointly the evidence, they did agree on facts, findings and recommendations on numerous issues."
It added that, despite differences over the conclusion: "Italy and United States are strong allies and enjoy a close and vibrant friendship, based on shared values and ideals."
The US military said the car in which Mr Calipari and Ms Sgrena were travelling was speeding as it approached a temporary checkpoint and failed to heed warning signals to stop.
Ms Sgrena, who was hurt in the shooting, said the car had not been speeding and that there had been no warning before the troops opened fire.
Italian Foreign Minister Gianfranco Fini said a separate Italian inquiry into Mr Calipari's death would continue.
Speaking after the statement was issued, Mr Fini said Italy would press on with a criminal investigation into Mr Calipari's death.
"For Italy, the courts will now do everything in their power, obviously backed by the government," he was quoted by AFP news agency as saying.
"One could not ask the Italian government to sign a reconstruction of events that did not correspond to ours."
State Department spokesman Adam Ereli said the US wanted to put any discord with Italy behind it.
"The mark of a strong relationship is to be able to work together to find the areas of agreement, to accept the areas of disagreement, to put them all in the proper perspective and then to move on," he said.
The death of Mr Calipari - who threw himself over Ms Sgrena to protect her from the gunfire - caused public outrage in Italy and intensified pressure on Italian Prime Minister Silvio Berlusconi to pull Italian troops out of Iraq.
Mr Berlusconi has been one of George W Bush's staunchest allies since the start of the war against Saddam Hussein in 2003.