The last time the Western allies went to war, during the Kosovo air campaign 30 months ago, Nato was in charge. But now, with the action over Afghanistan, Nato's military planners and headquarters have little to do. The Americans are running this war themselves, and it is unlikely that they will ever again wish to use Nato to manage a serious shooting war.
During its 52-year history, Nato has always had to perform both military and political tasks. But one effect of 11 September has been to highlight how much its political role – as a club for countries with similar interests and values – has grown at the expense of its military role. Vladimir Putin has been quicker to notice this transformation than many Western commentators. Speaking in Brussels earlier this month, the Russian president declared that "if Nato takes on a different shade and is becoming a political organisation", Russia would rethink its opposition to the alliance's enlargement.
Since the end of the Cold War, Nato's military job has shifted from territorial defence towards peacekeeping and, in the case of the Kosovo air campaign, some robust peacemaking. At the same time, Nato's rationale has become much more political. Both the Partnership for Peace programme, which links 26 states to Nato, and the enlargement of 1999, which brought the Czechs, Hungarians and Poles into the alliance, were designed to extend western Europe's stability and security eastwards. The fact that the three new members had inadequate armed forces – which subtracted from rather than added to the alliance's military effectiveness – was of less concern to Nato governments.
And now the Bush administration has made it clear that it will not use Nato's military organisation to conduct the war against terrorism. The Pentagon found the Kosovo air campaign a bruising experience. There were disputes between the Nato and American chains of command. Furthermore, acting through Nato meant working with committees, which the Americans often found frustrating. For example, France annoyed the US Air Force by blocking the bombing of Belgrade's bridges (thank God for French stubborness, many of us will say).
The US decision to run the current war through national commands makes military sense, given that Nato's own organisation has little of specific military value that can help in the fight against terrorism. Ironically, the decision to invoke Article 5 of the Washington treaty – the commitment to mutual self-defence that is often viewed as the core of the alliance – has highlighted Nato's marginal role in this conflict. It has also revealed Article 5 as a much looser commitment than many had imagined. The article states that each member has to "assist the party or parties so attacked by taking forthwith such actions as it deems necessary, including the use of armed force".
As one senior Nato official explains, invoking Article 5 imposes "a huge moral obligation on each member to provide what the US asks for". However, it is up to each member to provide such help as it sees fit. The US has requested the use of air space, ports and military bases, and for the transfer of some ships to the eastern Mediterranean. It has also asked for five of Nato's ground surveillance aircraft to fly to the US, to release American planes for Asia. The reason for the switch is that the US wants to avoid using Nato equipment in the war zone, for that would complicate its chain of command.
None of this means that Article 5 is unimportant. Moral obligations often produce results, as they have done in the current case. But the real significance of the article's invocation was to demonstrate the alliance's political solidarity with the Americans. Nato has offered the US unlimited diplomatic cover for whatever military actions it chooses to pursue.
Meanwhile the Balkans are moving rapidly down the list of the Bush administration's priorities. Europe already provides about 80 per cent of the Nato peacekeeping troops in Bosnia and Kosovo, and will be expected to take on more responsibility for the region's security. In Bosnia, which is now fairly peaceful, the administration may urge the EU to take over from Nato. One US official asks: "What is the point of a European Security and Defence Policy (ESDP) if it cannot manage a situation like Bosnia?"
If the US expects the EU to take over the easier sorts of peacekeeping, yet intends to run serious wars on its own, what military role remains for Nato? The answer is probably middle-sized problems, such as Kosovo, which the EU alone could not cope with. In the long run, however, if the embryonic ESDP makes progress, Nato's military role may be squeezed between American unilateralism and a more self-confident EU.
Nato's increasingly political character has implications for its future enlargement. Next November, at its Prague summit, Nato is likely to declare that Slovenia and Slovakia are ready for membership. Many Americans argue that Estonia, Latvia and Lithuania should also join, in order to enhance their security and stability. They appear unconcerned that the arrival of five new members would weaken the alliance's military cohesion. Most alliance governments are prepared to accept the Baltic countries. However, the British sometimes raise questions, pointing out that these countries would be hard to defend; but the British government is one of the last in Nato that continues to view it as serious military organisation.
The more political the alliance becomes, the easier it will be for Russia to accept Nato enlargement and to develop closer ties of its own. President Putin says that he wants changes in Russia's relations with the EU and Nato. In the past, Article 5 appeared to be a barrier to Russian membership of Nato: west Europeans did not find the prospect of an obligation to defend Russia's Asian frontier appealing. However, now that Article 5 has been seen to involve a fairly loose political commitment to mutual defence, rather than one that is absolutely binding, that barrier is lower.
So long as President Putin's government continues along a broadly democratic path, Nato should declare that it sees no fundamental objection to Russia joining at some point in the future. A Nato that included Russia would be in essence a political alliance – and a very valuable part of any global coalition that was committed to fighting terrorism and its causes.
The writer is director of the Centre for European Reform