In the first disorienting years after the Cold War, NATO began to see its future in the slogan "Out of area or out of business." It could hardly keep on organizing itself around defense of a line through Europe that no longer existed. If the alliance did not broaden its horizons, it risked irrelevance.

Successive U.S. administrations pressed this view, and the Clinton White House placed great stock in NATO's expansion--both in membership, embracing former Warsaw Pact members Poland, Hungary and the Czech Republic, and in its "strategic concept." The alliance could and should act to protect its interests beyond its central European neighborhood.

Only a few months ago, the North Atlantic Treaty Organization was entertaining notions of an agenda that would include crusading against global terrorism, drug trafficking and the proliferation of weapons of mass destruction. The war in Yugoslavia has brought the alliance back to its founding idea of ensuring security for the European continent, albeit in a region that was not part of NATO's mandate for its first half-century.

All the talk of broadening NATO's scope--toward broader threats, areas of operation or membership--fed fears among non-members of the alliance as "globo-cop." First among them was Russia, which former State Department official Arnold Kantor said sees Kosovo as confirmation "of their worst fears about the United States and NATO, with its new strategic concept that [it] can go anywhere and do anything . . . and the Russians aren't part of it."

Russian officials have begun arguing that NATO is sending the wrong message to smaller powers--that they must develop weapons of mass destruction to avoid another Kosovo. Clinton administration officials gave short shrift to that point, saying every country weighs many factors in deciding whether to become a nuclear rogue and that Kosovo is unlikely to be a large one.

"It would be ironic," one senior official said, "for any Russian official to suggest that what we did in Kosovo would create incentives for proliferation that weren't created by what they did in Chechnya," the Russian region where Moscow's troops fought a bloody and ultimately futile war against separatist rebels.

Early signs, in any event, are that NATO's first war has spooked the alliance as much as its potential foes.

"The war was fought because it was necessary, not because it was something designed or planned for," said one senior Italian policymaker, interviewed by telephone from Washington. "Obviously, nobody in his right mind would look with relish at the prospect of repeating this experience."

Momentum is certainly halted, for now, for extending NATO's reach to far-flung interests in Persian Gulf oil, the halt of nuclear weapons and missiles across Asia and the Middle East, or in fighting terrorist crimes on a transnational scale.

"NATO is like the guy who falls in the rapids and gets swept over the falls and survives," Johns Hopkins University Professor Michael E. Mandelbaum said. "He may lie to his friends and say he enjoyed it . . . but he sure as hell isn't going to try it again."

The allies are further preoccupied with the disparity of capabilities among them. German Gen. Klaus Naumann, the recently retired director of NATO's military committee, said the growing technology gap between the United States and its European allies could lead to their inability to fight or even communicate on the same battlefield. The United States, the richest of 19 NATO members but hardly richer than the others combined, has provided more than 80 percent of the 1,100 warplanes in the Kosovo air armada. Washington also has supplied nearly all the aerial intelligence and selected virtually every target to be struck.

So difficult were the politics of the war, and so costly the prospect of dispatching 50,000 peacekeeping troops into Kosovo, that the European consensus in NATO now is that this out-of-area gambit may be the last. Many strategists within the alliance expect the Balkans to become an absorbing ordeal that will tie up troops and resources for years.

"NATO is shifting from the plains of Germany to the hills and mountains of the Balkans," said one experienced diplomat. "We now have troops in Bosnia, Albania, Macedonia; Croatia is on the logistical route. We will have troops in Kosovo and I would guess in Montenegro. They are going to be there a long time. Like the troops who have been in Korea for half a century. No one would have thought they would be there that long."