“The most successful military alliance in history” is one description. Another is “brain dead.” And a third is “obsolete.”

The fact is that all the above descriptions of the North Atlantic Treaty Organisation are correct in varying degrees along with “guarantor of peace in Europe” and the “military heart of the Western Alliance.”

It is also true to say that the alliance is in crisis. To paraphrase Dean Acheson’s description of post-imperial Britain, NATO won the Cold War and has yet to find a new role in the world.

If one starts from the assumption that NATO is a force for good than it is essential that the alliance re-discover its role in the world. To do that it needs to re-evaluate the circumstances and values that led to its formation 70 years ago; examine how the world has stayed the same; how it has changed; and then change and adapt.

In 1949, the world was only four years out of a world war. America had emerged enormously wealthy, militarily powerful and armed with the world’s first true weapon of mass destruction. Its ideological enemy the Soviet Union had absorbed Eastern Europe and seemed poised to send its steamroller army across the rest of the devastated continent. It was four months away from detonating its first atomic bomb. Britain—which had been charged with the responsibility of protecting post war Europe—was broke and broken, and appealed to America to fill the vacuum. China was soon to “fall” to Mao’s communists and slip behind a bamboo curtain for 30 years. Former enemies Germany and Japan were as distrusted as the Soviet Union. There were only 59 members of the United Nations as most of the future 193-strong membership was still colonies.

NATO had a clear purpose: To protect the democracies of Western Europe from Soviet aggression so that they could recover from a devastating world war; preserve the shared values of economic and political liberalism; protect traditional markets and prevent a third world war. Lord Ismay, NATO’s first Secretary General, declared that the purpose of the alliance was to “keep the Americans in, the Russians out and the Germans down.”