What is the future for European relations with the United States? Are they set to become more equal after the strategic and political subordination of the post-1945 period - which did not greatly change after 1989?
Does this herald a more multipolar international system, governed by a robust multilateralism involving strong institutions with the power to enforce their will? Or is the 21st century also destined to be led by a hegemonic United States wielding global power, with the Europeans remaining junior partners - supplying services, carrying military bags and coming in after US interventions to provide funding for reconstruction and development, as in Afghanistan?
The events of September 11th threw such questions into the limelight, following a difficult first nine months in the European relationship with the new Bush administration. During this period Bush rejected the Kyoto agreement on global warming; abandoned an OECD scheme to combat money-laundering and tax evasion; resisted a special United Nations convention to stem the international flow of small arms; refused to sign an enforcement protocol for the Biological Weapons Convention; campaigned actively against the treaty establishing the International Criminal Court; determined to abandon the Anti-Ballistic Missile Treaty and withdrew from the UN conference in Durban on combating racism and xenophobia in protest against criticisms of Israel.
It is a formidable list, apparently signalling a determination to steer clear of alliances and treaties if they do not serve the US national interest narrowly conceived. It seemed to reflect a new balance of power in Washington under the Bush Republicans.
Many believe the international events since the September 11th attacks have irretrievably altered that unilateralist approach.
As the EU Commissioner for External Relations, Chris Patten, puts it (in an interview with the online journal openDemocracy) , prior to the attacks multilateralism was seen as appropriate for wimps, not for a superpower. After them it is not just a moral argument but a necessary security and national interest.
This view is symbolised in phrases used by Richard Haass, director of policy planning in the State Department. He defined US policy as an "a la carte multilateralism". In November he said "hard-headed multilateralism is not an alternative to leadership, but its manifestation". Asked how the EU can encourage such an engagement, Patten said Europeans needed "to shoulder responsibility for our own security", to demonstrate "the success of our experiment in pooled sovereignty" and "to tackle the dark side of globalisation".
That this was indeed the strategy followed by EU leaders after September 11th was confirmed by Charles Ries, assistant secretary for European affairs in the US State Department. In an interview he said that while the terms unilateral and multilateral are useful in academic policy analysis, they do not come up in the daily discourse of his department. September 11th represented first and foremost a classical attack on US national interests, calling for a military response. But it was seen as a worldwide challenge from the very beginning, calling for multilateral responses in the United Nations, with NATO and the EU. "Every step of the way we envisaged the operation in the context of working with other countries."
He does not deny that a "healthy policy debate" takes place within the Administration; but he prefers to think of it in terms of the triangulation technique popularised by President Clinton, in which many different US departments and agencies are involved, rather than as a continuum represented by the unilateralist Pentagon at one end and the multilateralist State Department at the other. In any case the US put reasoned positions in all the international forums where contentious issues were discussed before September 11th and did not walk out of them.
Mr Ries insists that the US welcomes a much more active EU role in the world as a more effective partner - of which the agreement to relaunch the world trade round in Doha was the perfect example.
The two have been working closely on the Israeli-Palestinian conflict, while the US recognises constructive differences over Iran and some tactical ones with EU states over sanctions on Iraq. There are tensions on both sides of the relationship, but pragmatic co-operation is increasingly the pattern.
As for equalisation, Mr Ries asks whether that implies US opposition to the development of the European Security and Defence Policy and the Rapid Reaction Force? The opposite is the case. NATO co-operation over Afghanistan freed up the US Sixth Fleet in the Indian Ocean to launch attacks.
The EU's actions under Belgium's presidency on terrorism, freezing assets and border security are "exactly what we wanted and are working really well", Mr Ries says. He expects that pattern to continue with the Spanish presidency from January. He commended Ireland's role in the UN Security Council since September 11th.
A senior EU official dealing with external relations says it is much too soon to say how the world has changed since September. The EU-US relationship is becoming more equal; the US faces no other international player of equivalent size or weight. Unilateral or isolationist policies are increasingly unrealistic. There will be many ups and downs in the relationship as it develops, but it is becoming more sophisticated.
The EU will need to learn how to react to events in real time, rather than waiting for committees to meet. But it has the patience and the structures for a more multilateral world relying on political not military means, from which it will benefit in the longer term. Putin's Russia is an ambiguous but necessary partner for the EU in coming years. NATO and EU enlargement will affect that relationship profoundly.
It remains to be seen whether such optimistic official perspectives express accurately the forthcoming US-European relationship. Much depends on how the terms multilateral and unilateral are defined. Critics say that in practice the multilateralism practised by the US since September is better described as strategic co-operation, since it carries no obligation for genuine reciprocity. It differs from "robust multilateralism" in not being committed to building institutions that could be enforced by international law, through the UN and/or new organisations like the WTO and the Kyoto Protocol.
This means it is easier for the US to maintain its hegemony and power behind a cloak of co-operation, they say. They portray an overall picture of a new informal western imperialism couched in the vocabulary of liberal cosmopolitanism and ethical intervention.
US public opinion is also engaged in this debate. A poll commissioned by the Pew Research Centre and the Council of Foreign Relations last October found that by two to one Americans say the US should strongly take into account the interests of its allies as opposed to taking decisions based mostly on national interests. This view is now shared across ideological groups. US writers such as the historian David Calleo argue the EU must be allowed the political space to develop long-term relations with Russia in a pan-European arrangement that could develop a more equal triangular relationship with the US, if the continent is to be stabilised and not disrupted by over-hasty NATO and EU enlargement.
Thus there are major issues at stake in this relationship, not only in the transatlantic arena but for overall power and influence in the world. US-EU relations are both co-operative and competitive, both of which aspects are intensified by the long-tern process of equalisation between them in economics, social affairs, diplomacy and security/defence issues.Events and political choices will determine how this is played out.
The Europeans are especially worried that hawks in the Bush administration will be tempted to strike against other states such as Iraq or Somalia in pursuit of al-Qaeda, thereby asserting their military power in the world and in the process dividing the Europeans.
But it may take precisely such a crisis to convince the EU that it should strengthen its own capacity for multilateral engagement in world affairs.