The United States will press NATO to create a permanent rapid reaction force to help improve the alliance's combat readiness in the face of terrorist threats, according to senior U.S. and European officials. The proposal is expected to be presented by Defense Secretary Donald Rumsfeld at an informal meeting of the 19 NATO defense ministers in Warsaw next week, the officials said. The goal of the consultations there is to win formal approval at the North Atlantic Treaty Organization summit meeting in Prague in November.

The initiative comes at a time when NATO is in the middle of an identity crisis, uncertain of its role, its future and even who its members will be. It also coincides with a redefinition by the United States, which spends more than twice as much on defense as the other 18 members combined, of what constitutes a military threat in the post-Sept. 11 era.

A senior Pentagon official said that the NATO rapid reaction force would be separate from the European Union's 60,000-member rapid reaction force, which is to be operational next year. The European force would be focused "on the low end of peacekeeping," while the NATO force would have to be involved in "high intensity" conflict, he said.

Foreign diplomats and military officers at NATO complained that the proposal was vague and the timing suspect. Senior diplomats said they had not been briefed in any detail by the Americans about the proposal. "We are waiting to see what kind of military requirements are involved," an ambassador to NATO said. "What will be the cost? What will be its mission? Its command arrangements? NATO is in the middle of expanding. Will this add to its burden and complicate the issue?" The ambassador noted that the goal of the summit meeting had repeatedly changed because of the Bush administration. "First it was enlargement, then it was all about capabilities, now it's all about a reaction force," he said.

U.S. proponents of the new force said it would consist of troops already part of standing armies and would work with the United States. It would function in small and highly mobile units under a new command to carry out combat missions on short notice outside Europe. "Can we develop in NATO a force that would be capable of rapid deployment, that would have the ability to respond to a crisis and be able to integrate with U.S. forces and have the technical capabilities necessary to do that?" asked General George Joulwan, a former NATO commander, who has written and spoken extensively on the issue. "What I gather Rumsfeld will put on the table is a way to do that."

Rumsfeld, a former ambassador to NATO, has made no secret of his skepticism about whether NATO has much of a military role to play. Asked by telephone from Washington about Rumsfeld's mission, Victoria Clarke, the Pentagon spokeswoman, said: "The secretary is going to have a lot of discussions. He's just not keen on us previewing his conversations."

For some time, Bush administration officials have broadly criticized NATO for its shortcomings. The administration wants to change the military structure of NATO so that it can react better and faster to the emerging global threats. Senior administration officials denied that the U.S. initiative had been aimed at garnering support from America's NATO allies for a military offensive against Iraq. One pointed out that NATO was already creating a high-readiness force involving tens of thousands of troops that would be operational by the end of the year. But the administration's decision to push the issue now dovetails with its campaign against terror and its war planning against Iraq.