NATO allies held an extraordinary meeting Monday to discuss American concerns that the European Union might create a military structure separate from the alliance.

A spokesman for the North Atlantic Treaty Organization said European countries "went to great pains" to assure the United States that a European military project would be intended complement NATO and would minimize duplication.

But it was unclear whether the meeting resolved the key question at the heart of American concerns: that a European Union military headquarters could conduct planning and operations outside NATO supervision and control.

U.S. officials, including Secretary of State Colin Powell, have said Europe should spend its limited resources on more defense within NATO, not a new headquarters. "All of the European allies went to great pains to reassure the non-EU allies, including the U.S., that we will have transparency, we'll have cooperation between the two organizations," Jamie Shea, the NATO spokesman, said in an interview after the meeting.

"They all share the view that we have to minimize duplication," Shea said.

The meeting took place in an atmosphere of relative secrecy. Only the ambassador and an assistant from each of the 19 NATO member countries were allowed to attend, and few of the countries' representatives briefed the media when the meeting ended Monday evening.

Defense analysts say U.S. diplomats have exerted heavy pressure on the British government in recent days to resist the French-German idea of a separate headquarters.

Prime Minister Tony Blair of Britain met with his French and German counterparts this month in Berlin to discuss defense cooperation in what appeared to be a policy shift for London.

President Jacques Chirac of France made it clear at a European Union summit meeting Friday that he intended to create a planning and operational headquarters for the EU. The move comes as European leaders debate a draft constitution for the European Union, which includes provisions on defense.

Chirac said, "Our British friends have reservations about the creation of a planning and operational headquarters." But the actual British position remains murky. "We are continuing our discussions," Chirac said. "But we have decided to pursue this project because we think that there will not be a Europe without a defense capacity."

Everyone involved, including Chirac, has said that the new EU planning headquarters would be "compatible" with NATO. That word, however, appears to be defined differently in European capitals.

Blair said at the EU summit meeting, "It is important that Europe has the capability to act independently." But he qualified this by saying that Europe should only act on its own "where America for one reason or another doesn't want to be involved."

He called NATO "the basis and cornerstone of our defense."

Blair did not specifically address the question of whether a headquarters would plan and conduct operations independent of NATO.

Analysts say Blair is sending mixed messages.

"He's trying to straddle the fence," said Radek Sikorski, a former Polish deputy defense and deputy foreign minister. "I hope he doesn't get impaled on it." The latest flap has aroused contradictory and ambivalent emotions in Europe, Sikorski said.

"On the one hand, people don't want the EU to become some kind of rival to NATO," said Sikorski, an analyst at the American Enterprise Institute in Washington, "but on the other hand, it seems to be another exercise of mixing the same amount of inadequate forces and just creating another staff for them."

Americans, he noted, would greatly prefer that the Europeans strengthen their actual military capabilities "rather than engaging in another bureaucratic contredanse."

"If Europe wants to get serious about defense, it should get serious about how it spends its defense money and what it will bring to the table, and then we will get the kind of respect and influence in Washington that as Europeans we crave," Sikorski said.

Another defense analyst, Samuel Wells, associate director of the Woodrow Wilson International Center for Scholars in Washington, said it remained unclear what the new European military structure would amount to.

"There's a lot of vague and sometimes contradictory information floating around," Wells said.

"My belief is that what the British are prepared to do is to have planning that like the old Kosovo formula is potentially separable but not separate.

"You keep a coordinated planning ar-

rangement but you have the capacity to separate in the occasion when the United States decides it's not going to participate."

Defense Secretary Donald Rumsfeld reportedly raised the matter last week with his British counterpart, Geoff Hoon, at a NATO gathering in Colorado.

The controversy has produced behind-the-scenes expressions of deep concern from the United States, but little on the record. That is probably because it involves the United States' closest ally in the war in Iraq, Britain.

On Monday, a Pentagon spokesman, asked about the matter, referred a questioner to comments made on Oct. 16 by the NATO secretary general, Lord Robertson, who in pleading for trans-Atlantic unity said: "This does not mean that we use NATO to address each and every crisis. It does not mean U.S. leadership in each and every case. Some problems might be better addressed by the EU, or perhaps by coalitions of the willing. In some cases, a division of labour will turn out to be the most practical solution.

"But whatever the best solution in individual circumstances, Europe and North America must always coordinate their approach and avoid working at cross purposes."

Wells said, "I am mystified as to why defense establishment here is making extensive public statements unidentified background statements about being very concerned about the British endangering NATO. "I think the British have pretty well established their bona fides on that and have paid quite a price for doing that."

Setting up a force would require not only having combat units earmarked to go, but also "getting the logistics and the intelligence straight, because if the U.S. is not going to participate, they've got to have allocated assets that cover some of the odd things the Europeans don't have," also including lift capacity, Wells said.

"In this whole area of establishing an independent European operational capability, they have two big tasks," he said. "The easier one is setting up a separable planning capability. The much harder one, given their budgetary restraints, is allocating new money to top-of-the-line forces that can operate together."

Other analysts are a bit perplexed about why Washington would seem so troubled about a potential European force that might largely deal with crises that neither the United States, nor NATO as a whole, might be inclined to deal with.