Less than a year ago, NATO's 50th-anniversary celebration was going to be a festive occasion. Alliance members were ready to toast each other for their ability to stand together against the Soviet threat and for having survived the end of the Cold War by forging a new relationship with their former rival and establishing a new raison d'etre. But as the heads of the 19 member states and the 23 NATO partners gathered in Washington last weekend, the mood was considerably more somber. The Balkan crisis has upstaged the festivities. Member governments now ask if they really understand NATO's place in a post-Cold War world, and if they are prepared for the challenges ahead.

For an organization whose existence was predicated on the threat from the Soviet empire, NATO took the collapse of its nemesis in stride. It quickly set up new relations with Moscow and the former Soviet satellite governments. The original 15 member governments walked a fine line in the process. They had to reward the newly liberated countries of Eastern Europe with security guarantees without raising fears in Moscow that Russia was being encircled. Russian sensitivities were respected and the opinions of its leaders were cultivated. Despite periodic broadsides from communists and nationalists, NATO succeeded in expanding its reach without triggering a reaction in Russia. Throughout it all, NATO maintained its internal cohesion without the glue of a Soviet threat.

The crisis in the Balkans has revealed how far NATO has yet to go if it is to survive for another half-century. The pressures of peacetime expansion are nothing compared to the stresses of conflict. U.S. President Bill Clinton, the host this past weekend, congratulated his allies on their ability to stick together through one of the gravest crises in NATO's history, but hanging over the meetings was the fear that, in a few years time, the celebrations this weekend might be looked at as a final farewell.