At any other time during the last 50 years, a summit meeting of the Western alliance would be a gathering radiating the unmistakable military power these leaders could throw against any security threat to Europe or the United States.
But after a year of U.S.-led combat operations in Afghanistan, where NATO countries played a marginal role, and now, with the prospect of war in Iraq, the grand alliance has never seemed more on the sidelines.
With President Bush here to meet with leaders from NATO's 18 other member states and to welcome seven new members, the most urgent task facing the assembly will be to rescue the alliance from obscurity.
"The fact of the matter is that the main threat is gone and NATO has become far less relevant," said James Schlesinger, a former U.S. defense secretary who spent a Cold War career burnishing a trans-Atlantic military machine designed to defend Europe and the West from Soviet and Warsaw Pact forces.
Nonetheless, a resuscitation package for NATO has taken shape in the wake of the Sept. 11 attacks, one that goes well beyond the retooling and reform that has been a work in progress at NATO's Brussels headquarters since the Soviet Union disappeared.
The effort is centered on creating a NATO rapid response force that could move swiftly with light, high-technology weapons around the globe to strike at new threats from terrorists or rogue nations with weapons of mass destruction. First broached by Defense Secretary Donald Rumsfeld at a meeting of NATO defense ministers in late September, the new template would bring NATO closer into alignment with the Bush administration's military strategy. The reach would be more global than previously sketched plans for an all-European defense force.
In the new NATO, commanders would ease requirements that all states contribute proportionately to the common defense. Instead, contributions could be based on areas of specialization, as Bush referred to it on Monday, an idea that allows the smaller and weaker members to find a "niche" in NATO's force.
One country could provide a unit trained for mountain warfare, another could contribute decontamination teams for troops facing chemical or biological weapons, another military police.
In effect, this would be an extension of strengths already demonstrated. The Czechs, for example, might be able to deploy units specializing in chemical warfare _ as they did in 1991 _ if Iraq mounts such an attack.
Still, a number of experts say that it could take years for NATO to emerge as an effective global military alliance, due in part to strained budgets in Europe and enormous gaps in military capabilities among member states, but also to political divisions on the continent over America's role as the dominant power.
George Robertson, NATO's secretary-general and the most ardent booster for reinvigorating the alliance, acknowledged those divisions in a recent speech in Berlin. He said that fundamental questions were afoot about the alliance's future, among them: "Is Washington committed to genuine multilateralism?" and, "How can Europe exert more influence on the world's only superpower?"
"The urge to find answers to these questions," he said, "must not distract us from the fundamental issue: The trans-Atlantic relationship remains indispensable for our safety and security."
In the first decade after the Soviet collapse, NATO showed that it could adapt for interventions on the periphery of Europe when ethnic conflict in the Balkans threatened to destabilize the continent.
But the Sept. 11 attacks and the Bush administration's deployment of military forces to Southwest Asia _ followed by the buildup under way in the Persian Gulf near Iraq _ present NATO with a more profound question: Can a multinational alliance reach a consensus on when and how to attack terrorists or rogue states threatening Western security?
Most Europeans devoted to maintaining the trans-Atlantic bonds created during World War II have watched and listened with puzzlement and pique to the policy arguments emanating from Bush's Washington. There, many conservatives have argued that formal alliances may be a thing of the past since they limit America's ability to act decisively and on its own schedule.
Schlesinger said it may be inevitable for the major Western powers to drift apart under the pull of domestic politics and economic strain. Chancellor Gerhard Schroeder of Germany has already declared his unwillingness to take part in military action against Iraq.
"Since the collapse of the Soviet Union, I've said the most important thing is the North Atlantic alliance itself, not its military capabilities," Schlesinger said. He urged leaders to look at "the psychological bonds of the North Atlantic Treaty, and the North Atlantic alliance that does not inevitably continue to drift apart."
Indeed, Schlesinger said, "If you get a couple more terrorist events in Europe so they feel they are as much under attack as we are, then I think you would see the alliance to begin to adhere again, and not because of military capabilities."
Yet this summit is very much about military capabilities. If NATO does not get new abilities to move forces rapidly and connect them electronically, NATO could devolve into a political club in which those members with modern military forces would act outside the alliance, together or separately, depending on calculations of national interest.