That is, the risk inherent in approaching roadblocks manned by troops of the U.S.-led coalition or Iraqi police.
One of RFE/RL's journalists in Baghdad, Muhammad Khadar, explains that people are nervous whenever they go out into the streets of the capital, and that tension rises when they approach a roadblock. "They are afraid of the suicide car bombs, and the explosions which usually happen near these roadblocks," he said.
The soldiers and policemen know they are targets for determined insurgents, and are alert for trouble that can develop in seconds. Khadar adds: "They expect a blast at any time, so their fingers are on the trigger, and they can shoot at any time."
And this is the heart of the matter in the Calipari case, the tragic occurrence on the road to the airport on 14 March.
Did the soldiers at that particular roadblock follow the proper procedures for warning an approaching car in the darkness, as the U.S. military says? Or did they shoot without first determining who was in the car, as Italy claims?
On 30 April, the United States issued a report on the incident based on a joint investigation by American and Italian officials. But the Italians on the panel refused to endorse the findings, and withdrew from it.
The American account is basically that the seven men manning the roadblock saw a car approaching at high speed in the darkness. The report claims the men used arm signals, lights, and warning shots in an attempt to make the vehicle stop. When it did not stop, one of the men fired shots at the car's engine.
The U.S. report contends that neither American military authorities nor diplomats had been informed in advance of the Italians' intention to take the freed hostage to the airport, along what is known as one of the most dangerous roads in Iraq.
The report also attaches no blame to the American soldiers on duty that night.
The official Italian account, released in Rome today, is quite different. The report says that safe-passage for the journey had been secured in advance from the American authorities. It claims the car had been traveling at moderate speed, and stopped immediately when a light was pointed at it. Then, the report adds, shots were fired into the car without further warning.
The Italians also say they believe "inexperience and stress" may have contributed to the soldiers' reactions that night. The report also says that the temporary American checkpoint was not clearly visible to approaching vehicles.
What's certain is that Calipari was killed, after throwing his body protectively across the freed hostage, Italian journalist Giuliana Sgrena.
Sgrena, who had just undergone a life-or-death ordeal as a hostage to Iraqi militants, was wounded.
Italy and the United States have been firm friends since the end of World War II. But this incident has dimmed, at least temporarily, the warmth between them.
However, officials from both sides have sought to show that the friendship will not be undermined by the tragedy. Speaking at a U.S. war cemetery in southern Italy today, U.S. Ambassador to Italy Mel Sembler said that America lost a "good friend" in Calipari. "As you can see today, relations between the United States and Italy are strong and will remain strong," he said. "This is a 60-year relationship, [but] there are bumps along the road. This is a terrible tragedy with Nicola Calipari. Nicola Calipari was a hero to the United States as well as to Italy."
At the same ceremony, the president of the lower chamber of the Italian Parliament, Pierferdinando Casini, said the two countries must face the issues that now divide them with the same spirit that was shown by the soldiers whom they were honoring.
He said the Italian report on Calipari had been compiled in the name of "truth, or clarity, and of mutual loyalty." "Only in this way," he said, "will we rightfully honor the martyrs of freedom, including the many that are resting in this very field."
The Calipari incident has led to some calls for Italy's 3,000 soldiers in Iraq to be returned home.