NATO, which won the Cold War without firing a shot, faces a crisis over Iraq that may damage or even cripple the world's most powerful military alliance.

Although the NATO dispute was triggered by opposition from some European nations to a U.S. attack on Iraq, it has as much to do with questions about Europe's future, its relations with the United States and what NATO is for.

"This is the biggest crisis NATO has faced in 30, 40 years," said Prof. Michael Clarke, a defense analyst at London University.

NATO will survive the dispute over Iraq because most of the European members are committed to an alliance that is the bedrock of their defense, analysts say. Still, NATO could be weaker, less united and uncertain about its role.

The dispute began with France, Germany and Belgium blocking the start of planning to defend alliance member Turkey against an Iraqi attack. The real argument was over Washington's determination to disarm Iraq.

The wrangle over Turkey threatened NATO's overriding principle that it exists to defend its members -- that an attack on one is an attack on all. Any failure to uphold that principle threatens the alliance of the United States and 18 nations.

A big question mark has hung over NATO since the end of the Cold War. Created in 1949 to defend Europe against the Soviet Union, the alliance has struggled to find a new role after the Soviet collapse.

With no serious or foreseeable threat, critics claim NATO no longer has a role and the United States uses the alliance to impose its will on Europe. The United States is not interested in treating allies as equals, the critics claim.

European supporters of NATO worry the bickering could anger Washington and it could walk out, leaving Europe without strong defenses. The United States is so powerful it does not need allies in any military conflict, they say.

"It's less important than it would have been during the Cold War when keeping NATO together was so important for deterrence purposes," said Tim Garden, a defense analyst at King's College, London.

But NATO is not likely to collapse in the foreseeable future because it remains vital to the Europeans and useful to the United States, many analysts say. There is little desire to dismantle what is seen widely as the most successful defense alliance in history.

Most European nations spend very little on defense. Losing NATO and the U.S. defense umbrella it provides would force them to spend much more if they wanted a credible defense.

And while the United States complains about Europe's low defense spending and political indecision, the alliance is useful to Washington, adding to its global authority and providing allied forces and bases.

"We've been through this before ... I think in the end that reason will prevail and we will have consensus on this issue," said retired Gen. George Joulwan, a former commander of NATO.

Britain and other strong U.S. allies in Europe are determined to keep NATO alive. Eastern European nations who have joined or hope to join NATO and are taking an increasingly important role on the continent are fervent supporters of the U.S. alliance.

NATO has survived major crises, including disagreement over the Anglo-French seizure of the Suez Canal in 1956 and basing of U.S. cruise missiles in Europe in the 1980s. France pulled out of NATO's military command in 1966, forcing America to move its French bases and the alliance's headquarters.

The current dispute is as much to do with the future of Europe as with the Iraq crisis. France has dreamed for years of a European military alliance under its leadership that would replace NATO and rival the United States.

France and Germany, which have led the European opposition to any U.S. attack on Iraq, are fearful of losing their traditional dominance in Europe as pro-U.S. eastern European nations join NATO and the European Union. The French want to reduce U.S. influence in Europe in the hope that Paris can step in to America's shoes. But few Europeans want to trade NATO for a French-led alliance that would be weaker and even more fractious.

NATO could evolve into a more flexible alliance that continues to provide a common defense, agreeing to disagree when necessary, some analysts say. The United States may form ad hoc alliances with some NATO members to respond to particular situations, they say.