Was the killing by US troops of an Italian security chief and the wounding of the Italian journalist he had helped release hours earlier an unfortunate tragedy? Or was it something more sinister? Either way, Washington has some tough questions to answer. American military sources in Baghdad maintain that the car carrying journalist Giuliana Sgrena and three Italian intelligence officials, including the slain officer, failed to react to repeated instructions to stop at a roadblock just outside the capital’s airport. It seems extraordinary that Italian intelligence professionals who had just rescued the journalist would have been insensitive to the requirements of a security check and the risks of ignoring it.

One possible explanation for the attack on the car carrying the Italians is that trigger-happy US troops, terrified of car bombers, fired the minute they suspected the vehicle was a danger to them. It only takes one nervous soldier to shoot a single bullet and a whole unit then shares the panic and opens up on a target. If this is what happened, then it is a demonstration of the indiscipline and poor training of US soldiers which has in the past resulted in a number of similar attacks, including the slaying of the Iraqi occupants of a car rushing a pregnant woman to a maternity hospital.

The odiously named “friendly fire” has characterized the US military performance in Iraq to the fury of Washington’s allies, not least the British whose troops have discovered that however “friendly,” it can prove as deadly as the unfriendly variety.

There is, however, the more sinister explanation which is that the Americans wanted Sgrena dead. A senior correspondent for the Communist daily, Il Manifesto in Rome, the journalist has been no friend of the US invasion and occupation. US troops have killed journalists before. Two cameramen, a Ukrainian and a Spaniard, were slain in April 2003 when a US shell was fired into the Palestine Hotel, a known base of international journalists opposite the Baghdad Sheraton. Earlier an Al-Jazeera correspondent was killed when the TV station’s local office was struck by a US missile.

The American military has not taken kindly to foreign journalists who refuse to involve themselves in America’s well-oiled media-relations machine. When Sgrena was kidnapped on Feb. 4, other journalists were told by US officials that the event highlighted the danger of working outside their Green Zone-focused loop. There was also apparently grim satisfaction that a journalist who was so opposed to US policy should have become a victim of the insurgents. The conclusion of the sinister explanation must therefore be that the Americans were settling the score with a foreign commentator whose published views infuriated them. Yet it seems incredible that even the American military could be this crass.

In Italy, the incident is provoking a renewed outcry against further Italian involvement in Iraq. An anguished Berlusconi reportedly made an extremely angry phone call to President Bush and was promised that that incident would be fully investigated. The journalists group Reporters Sans Frontiers is demanding, however, that an independent inquiry be mounted by the UN since the group fears that, as with the Palestine Hotel deaths, the US will again exonerate its trigger-happy troops.