WORLD VIEW: In a famous formulation, NATO's first secretary general, Lord Ismay, defined its purpose as: "To keep the Russians out, the Germans down and the Americans in Europe". This week's summit can best be understood in the light of a different formulation, coined by the French international relations scholar, Dominique Moïsi, who says that in the new world order "the US fights, the UN feeds and the UN funds."
It has taken 13 years since the end of the Cold War to reach this point where so many of NATO's former antagonists have now become members of the alliance, while the rest are bound up with one or other of its co-operating organisations. In the process, the Russians are accepted as a major European power, while Germany has become the European Union's largest and most influential member-state. The big question now is whether the United States will remain in Europe in the same way as it has for the last half-century. An officially denied remark by a leading Pentagon official this week illustrates the difficulties involved: "NATO: keep the myth alive."
There are two influential interpretations of this question, offering differing perspectives on the transatlantic alliance. According to the first, that era of close co-operation is coming to an end. A more unilateralist US leadership no longer has the political or military incentive to be constrained by a military alliance of 26 states working by cumbersome consensual procedures.
Its defence focus goes well beyond Europe and is now dominated by the international war against terrorism. Its military budget far outstrips the combined ones of its allies, while a growing technology gap renders their armed forces' inter-operability increasingly redundant. Many senior administration officials in Washington view Europe more as a nuisance than a partner.
This was illustrated by its dismissive attitude to NATO's first ever invocation of the mutual defence commitment days after the September 11th attacks last year.
Besides, the transatlantic relationship is becoming much more equal economically and politically, although not in the defence and military domains. Different interests and values are emerging as political integration binds the EU more closely together. Inevitably these will crystallise into differing perspectives on world affairs - as the current tensions over Iraq and terrorism illustrate.
Summing up this argument, Charles Kapchun, professor of international affairs at Georgetown University, senior fellow at the influential Council on Foreign Relations in New York, and a former senior official in the Clinton administration, concluded in a Financial Times article on Monday: "Pronouncements emanating from Prague this week will no doubt affirm that the Atlantic Alliance is in need of rejuvenation. At best, however, it will merely postpone NATO's inevitable demise."
He develops his case in his book, The End of the American Era. The unitary western world of the Cold War, with its common liberal internationalist logic and coherence under US leadership, is being superseded under the influence of two fundamental trends: the emergence of Europe as a more collective entity; and the changing nature of the United States, where political and demographic developments are transforming the post-war emphasis on Europe and reasserting unilateralism and isolationism, two sides of the same coin.
Kapchun draws fruitful comparisons between current developments in Europe and the evolution of US history in the nineteenth century.
He compares the western enlargement of the US in the nineteenth century to the eastern enlargement of the EU now under way.
The US, he argues, is changing fundamentally as political and economic elites from the south-west and its geographical heartlands displace the more internationalist elites who governed it for most of the last century.
In his view, that process will continue irrespective of which party has power in Washington.
In this perspective EU enlargement is a much deeper and more far-reaching process than NATO's. One has only to compare the public attention both have received to appreciate that fact. The seven countries accepted into NATO in Prague - Estonia, Latvia, Lithuania, Romania, Bulgaria, Slovakia and Slovenia - were only decided upon in the last few weeks.
They will have to restructure their armed forces and defence ministries and regard NATO membership as a crucial guarantee of security and linkage to the West. But EU membership is more encompassing and intrusive.
On an alternative view, the NATO enlargement signifies a renewed US commitment to Europe and a reassertion of its leadership.
The creation of a NATO rapid reaction force of 21,000 troops available to take action outside the European area will maintain the transatlantic alliance and bolster its more political role with an extra security commitment.
This is likely to involve continuing US leadership and implies that the European allies will accept that and the associated doctrine of preventive intervention to maintain US military hegemony formulated to justify it this summer.
It further assumes that the battles between unilateralists and mutilateralists in Washington have been resolved in favour of those who believe US military power cannot be used effectively on its own.
On this view, NATO is a necessary part of the international architecture to maintain US world leadership. But will the Europeans accept this structure of power and the subordinate role it implies?
That is a large assumption indeed. On Iraq and the Middle East there are growing rifts, which are likely to be exacerbated by a war next year. Public opinion in Europe will not accept the role implied by Dominique Moïsi's formulation.
That means developing a more coherent EU foreign and defence policy - not to replicate US power but driven by alternative assumptions, interests and values in coming years.