Italians are feeling indignant. According to a Milan judge, the US mounted a secret intelligence operation inside Italy, kidnapping a suspected terrorist as he walked the streets of Milan and whisking him to Cairo without letting Italy know.
Italians say the operation, if proven to have been masterminded by the CIA, was not just illegal but disrespectful to a sovereign state that is one of America's closest allies.
But the case - in which Italian magistrates are seeking the arrest of 13 suspected CIA agents they claim carried out the abduction - is not just the latest thorn in the side of Italian-American relations. It also exposes a wider clash of cultures between America and Europe when it comes to tackling terrorism.
"The Americans treat this as a war, but the Europeans still see this as a criminal-justice matter," says Ian Cuthbertson, counterterrorism expert at the World Policy Institute in New York.
"Americans think they are fighting evil and that you can't play by the rules when you fight an enemy that does not," says Dr. Jörg Friedrichs, an expert in international police cooperation at the University of Bremen in Germany. "But in general, Europe, with its history of dealing with domestic terrorism, is convinced that the problem must be tackled using the law, not flouting it."
"We have learned that as a democratic country you must abide by the law," says Alessandro Politi, an analyst at the Cespi institute in Rome. "You cannot think that all means are justified by the end. If you circumvent the law, that is the best possible propaganda you can give to the enemy."
Italian judicial investigators say they were close to arresting the Egyptian cleric, Hassan Mustafa Osama Nasr, otherwise known as Abu Omar, when he disappeared in February 2003. Italian investigators say they had passed on to their US counterparts information gleaned through wiretapping and surveillance that the imam was attempting to set up a jihadi recruitment network in Europe.
But European judicial inquiries, which are independent from state intelligence operations, must work painstakingly to build cases against suspected terrorists, and arrest them only when there is sufficient evidence for a court case. America's approach since 9/11, however, is to eliminate the threat first and ask questions later.
"Americans will never think Europe is doing enough," says Cuthbertson. "For every hundred terror-related arrests, only a handful are ever convicted. And even then, sentences in Europe for any crime are trivial compared to those in the United States. Suspected terrorists are often allowed to walk free.
In the case of the Milan abduction, he says, "the Americans felt the information this man had was too valuable; if they entered into the European justice system, that information would never come out."
President Bush has openly acknowledged that in its war on terrorism the US has resorted to "extraordinary rendition" - plucking individuals from third countries, bypassing normal expulsion procedures, and handing them over to their countries of origin.
Last month, the Egypt Prime Minister Ahmed Nazif told NBC news last month that between 60 and 70 terror suspects have been dispatched to Egypt this way since September 11, 2001.
In most cases, local authorities give tacit consent, detaining the suspects and then handing them over to the American officials who spirit them away. But most cases are not reported.
All told, human rights organizations say they have identified between 150 and 200 cases of rendition since September 11, in many cases to countries with reputations for torturing detainees, such as Egypt, Syria and Uzbekistan.
The United States acknowledges it has delivered suspects to many countries, but insists it does this only with assurance that they will not be tortured.
In Italy, neither US nor Italian officials have acknowledged a role in the disappearance of Mr. Nasr, who is thought to be in an Egyptian prison now.
While formal relations between the two governments remain strong, the arrest warrant issued by an independent judge, which names suspected CIA agents, is likely to reduce the levels of trust between the two allies in future.
"Exchange of information between US and EU countries is generally based on a 'you give me this, I give you that' case-by-case approach," said one European Union official, who asked not to be named.
"It's crucial that there is a feeling of collaboration. Any perception - real or not - of disregard for one country's interests will have a damaging effect and may complicate matters Europewide."
Within Europe different countries have varying degrees of information exchange with the United States over terrorism investigations.
"Italy may be on America's side in Iraq, but cooperation with the French and the Germans on counterterrorism operations has been better," says Cuthbertson. Some say this is due to American objection to Italy's suspected policy of negotiating with terrorists, paying ransoms if necessary, for the release of hostages held in Iraq.
"The Italians have always been short changed. Even though Italian investigations have significantly improved in recent years, they have a reputation for being lax. The Americans do not give them as much information as they do to larger EU countries."