At the heart of the alliance is article five of the North Atlantic Treaty: if one NATO member is attacked, all will respond. Now, as US President Obama reminded us in Strasbourg, NATO “remains the strongest alliance that the world has ever known.” NATO’s summit, however, revealed the weakness of that alliance. Contrary to the spirit of the NATO treaty, some countries are doing much more in Afghanistan than others. The discrepancy is so great that it is almost misleading to call it a NATO mission. Countries cannot share the benefits of collective security without sharing its burdens too.