The origins of NATO

It's been called the most successful alliance in world history. President Obama and fellow leaders of the North Atlantic Treaty Organization, NATO, are meeting at an important summit in Chicago this month to discuss the future of the alliance.

NATO troops have now spent a decade in Afghanistan, and more recently, NATO airpower helped to overthrow Moammar Ghaddafi in Libya. But in the face of economic stress, and war-weary publics in the United States and Europe, how will the alliance move forward?