One of the most significant fallouts from the U.S. war on terror has been the strain on America's historically strong relationship with Europe.

Allegations of secret CIA prisons in Europe and European governments' complicity with the kidnappings of terror suspects (known as "extraordinary renditions") have irritated trans-Atlantic relations, stressed the NATO alliance and jeopardized U.S. national security priorities, including maintaining an international coalition in Iraq.

Allegations began to surface about secret CIA prisons in Europe in late 2005, after the Washington Post revealed the existence of "black site" prisons there. By the time the European Parliament released its initial findings about the covert program in June 2006, European public outcry was swift and shrill.

"Bush exposes not only his own previous lies," said Sarah Ludford, a British member of the European Parliament, "he also exposes to ridicule those arrogant government leaders in Europe who dismissed as unfounded our fears about extraordinary rendition." In that practice, military or intelligence agents operating outside the normal judicial system seize terrorist suspects and spirit them away for questioning in secret locations, often to countries known to employ torture.

Evidence of covert cooperation between the CIA and European intelligence agencies continued to mount. Revelations about the involvement of Italian intelligence services in the abduction of Egyptian-born cleric Abu Omar off the streets of Milan shook the Italian government and has led to the indictment of half a dozen Italian officers as well as 26 Americans. It also led to a constitutional crisis in Italy, with the government claiming that state secrets should trump the judicial investigation and prevent disclosure of documents that could confirm Italian complicity in the CIA kidnapping.