The North Atlantic Treaty
Washington D.C. - 4 April 1949
Article 5

"The Parties agree that an armed attack against one or more of them in Europe or North America shall be considered an attack against them all and consequently they agree that, if such an armed attack occurs, each of them, in exercise of the right of individual or collective self-defence recognised by Article 51 of the Charter of the United Nations, will assist the Party or Parties so attacked by taking forthwith, individually and in concert with the other Parties, such action as it deems necessary, including the use of armed force, to restore and maintain the security of the North Atlantic area.

Any such armed attack and all measures taken as a result thereof shall immediately be reported to the Security Council. Such measures shall be terminated when the Security Council has taken the measures necessary to restore and maintain international peace and security . "

http://www.nato.int/docu/basictxt/treaty.htm

And from:
http://www.nato.int/docu/review/2006/issue2/english/summaries.html
"Article 5 of the Washington Treaty was envisaged by the Treaty's signatories as a mechanism obligating the United States to come to the aid of its European Allies. But when the Treaty's defining clause was first invoked, it was the European Allies who offered Washington their support in the wake of the 9/11 terrorist attacks. The ramifications of this invocation are still emerging in ways that reflect the document's original composition. The Washington Treaty was a compromise: while the obligation to come to the aid of an Ally under attack was automatic, the treaty's wording allowed Allies the freedom to choose the nature of their response. The Alliance's founding fathers could never have predicted the scenario in which Article 5 would be invoked. Despite Washington's initial decision to decline NATO support for the 2001 campaign in Afghanistan following the 9/11 attacks, 14 of the then-19 NATO Allies contributed forces. Article 5's invocation set in train NATO's ongoing transformation as the Alliance developed terrorism-related competencies and created the NATO Response Force. Some believe that Article 5 may come to be understood as having direct relevance to the Allied response to new and evolving challenges.
...
Once it had been determined that using an aircraft as a weapon constituted an 'armed attack' in the sense intended by Article 5 and that the attacks were qualitatively different from "normal" domestic terrorism..."

I will repeat, "But when the Treaty's defining clause was first invoked, it was the European Allies who offered Washington their support in the wake of the 9/11"

Apparently, 14 of 19 NATO countries had a slightly different view of it than Raoul.