From Ivo Daalder, the Wall Street Journal:  Yesterday we all remembered that day 10 years ago, when terrorists turned airplanes into weapons of mass destruction. But we should also remember what happened the following day. On Sept. 12, 2001, the North Atlantic Council, the NATO Alliance’s governing body, met in special session. For the first time since NATO’s founding in 1949, the council decided unanimously to invoke Article 5 of the North Atlantic Treaty, saying that the attack on 9/11 was not just an attack on the United States but an attack on all the members of NATO.

Within hours of this historic meeting, NATO’s Airborne Warning and Control System aircraft were alerted for deployment in the skies over America. They patrolled our vast airspace for the next five months.

The invocation of Article 5 was a defining moment for NATO. Until that moment, everyone had assumed that this commitment of the treaty was designed to involve the U.S. in the defense of Europe. No one imagined that it would first be used to bring Europe to the defense of the U.S. But with this one act, NATO signaled a fundamental change in its mission. All of us now recognized that security in Europe and in the U.S. was inextricably connected to events far beyond NATO’s traditional areas of operation. NATO had to stop thinking regionally and begin thinking globally.

Today, five of NATO’s six current operations are outside of the alliance’s territory. NATO’s soldiers are fighting in the very territories of Afghanistan where the 9/11 terrorists trained and planned their heinous attacks. NATO ships are taking part in an antipiracy mission in the Indian Ocean, and NATO forces are training Iraqi soldiers, stabilizing the situation in Kosovo, and still protecting Libyan civilians against the remnants of the regime that had tried to suppress their freedom.

Mr. Daalder is the U.S. ambassador to the North Atlantic Treaty Organization.  (photo: Allied Command Operations)

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