MUNICH, Germany - Defense Secretary Donald H. Rumsfeld issued uncompromising challenges to the United Nations and NATO over Iraq yesterday, warning that the global body risked ridicule and discredit and cautioning three of America's European partners that delaying plans to defend Turkey weakened the Atlantic alliance.

As Rumsfeld spoke, thousands of people joined a protest called by church and labor leaders in the heart of Munich to protest a potential war in Iraq.

Meanwhile, the two senior U.N. weapons inspectors landed in Baghdad on what could be their last visit, seeking significant moves by Iraq to prove that it has disarmed.

Rumsfeld said that the United Nations, by allowing Iraq to violate 17 Security Council resolutions over more than a decade, appeared to be following the League of Nations in choosing bluff over action.

Allowing Iraq to chair the U.N. Commission on Disarmament and selecting Libya to lead the U.N. Commission on Human Rights showed that the institution "seems not to be even struggling to regain credibility," he said.

"That these acts of irresponsibility could happen now, at this moment in history, is breathtaking," Rumsfeld said. "Those acts will be marked in the history of the U.N. as either the low point of that institution in retreat, or the turning point when the U.N. woke up, took hold of itself and moved away from a path of ridicule to a path of responsibility."

Turning to America's NATO partners, Rumsfeld was critical of France, Germany and Belgium for what he said were "inexcusable" actions to postpone alliance planning to defend Turkey in the event of war with Iraq.

"Turkey will not be hurt," Rumsfeld said. "The United States and the countries in NATO will go right ahead and do it. What will be hurt will be NATO, not Turkey."

Kofi Annan, the U.N. secretary-general, said yesterday in a speech at the College of William and Mary that the United States should not try to break the Security Council's unity on Iraq and that it should take time for "patient" negotiations before launching a war.

NTV, a Turkish-language news channel, reported that Turkey's leaders had agreed to accept up to 38,000 American troops for an operation in Iraq and that they would allow American planes to use six Turkish air bases.

Senior Turkish leaders, who were meeting with American diplomats, were not available for comment, and the report could not be confirmed. The Turkish Parliament, which would have to approve such an agreement, is scheduled to vote Feb. 18 on whether to allow American troops to use the country for an attack on Iraq.

German response

In an animated rebuttal to Rumsfeld, Joschka Fischer, the German foreign minister, said that his nation was not abandoning its obligations to defend Turkey, but suggested that NATO planners await the next report of the weapons inspectors, which is scheduled to be presented Friday.

"We didn't want an extra buildup to be done, so to speak, before the decisive Security Council meeting," Fischer said. Proposals for NATO's defense of Turkey include deploying Patriot anti-missile batteries and surveillance aircraft.

Fischer said he had no arguments with the American assessment of Saddam Hussein as a dictator who has fired Scud missiles at his neighbors and used chemical weapons.

"Why this priority now?" he asked Rumsfeld. "We have known this for a long time."

Fischer recounted Germany's arguments for international inspectors to continue their efforts in Iraq, especially given new intelligence disclosed last week by Secretary of State Colin L. Powell, and he rejected the American case for military action.

"I am not convinced," Fischer said. "This is my problem."

The influential Der Spiegel weekly, in advance copies released yesterday, reported that France and Germany were considering a plan to deploy thousands of U.N. peacekeepers and hundreds more weapons inspectors to prevent military conflict in Iraq.

Livid American officials denounced the fact that they first heard of the plan from reporters.

"That's not the way to have a winning hand with the United States," said a senior American official. In fact, the official said, Rumsfeld asked German Defense Minister Peter Struck about the report and was told, "We're not ready to talk yet."

The American official indicated that the United States would not support the plan, pointing to the failure of U.N. forces to prevent massacres in Bosnia.

A German government spokesman confirmed that the two nations were working together to find a peaceful alternative to war, but he declined to give details.

Views of terror threat

Meanwhile, the lively exchange yesterday between Rumsfeld and Fischer occurred during an annual conference on international security - at which former directors of the CIA mingle with Russian national security chiefs, and government ministers meet in formal bilateral sessions and in elegant private dinners. Legislators from across Europe ate smoked salmon as protesters gathered in a light snow on the nearby Marienplatz.

The gap between American and European views of the global terrorist threat was summed up by Edmund Stoiber, the premier of the German state of Bavaria, who said, "The dangers are not perceived in this breadth and width."

Rumsfeld's theme that the nations of the world faced a momentous decision was echoed by Sen. John McCain, an Arizona Republican, who told the conference that France and Germany had dealt a "terrible injury" to the alliance and "raised doubts among nations on both sides of the Atlantic about their commitment to multinational diplomacy."

Despite Rumsfeld's lengthy public criticism of the United Nations for its handling of Iraq, he spoke with his Russian counterpart, Sergei B. Ivanov, of the important role that its International Atomic Energy Agency must play in defusing the current nuclear crisis in North Korea.

During a closed-door meeting of the two defense ministers, Rumsfeld and Ivanov agreed that North Korea posed a threat to the world and that it should be dealt with as an "international problem," according to a senior Defense Department official.

Even as he rallied support for a possible war with Iraq, Rumsfeld turned to humor to appease irritated allies.

Rumsfeld made light of his description of Germany and France as the "old Europe," whose opposition to war with Iraq he contrasts with support for the United States from Britain, Italy and a number of post-Communist nations that are new to NATO and the European Union.

"At my age," said the 70-year-old Rumsfeld, "I consider 'old' a term of endearment."

Eastward shift

But Rumsfeld got in a subtle dig at Germany, which in the 1990s saw itself as a unified nation at the heart of Europe with influence increasing to the east. "The center of Europe has indeed shifted eastward," Rumsfeld said, pointing out that the United States was pleased with the new alignments within the alliance.

The post-Communist nations - or at least many of their current leaders - see the U.S. as a power whose championing of liberty proved decisive in the defeat of communism. Unlike France or Germany, these nations also have no history of irritation and bickering in the post-1945 Atlantic alliance.