Since September 11, the task of building a European defence capability has become more urgent and more complicated. The war in Afghanistan has exposed, once again, Europe's limited scope to combine its military forces. The new terrorist threat suggests the European Union's emerging security and defence policy may have to be adapted to changing needs.

When defence ministers gather today in Brussels, Javier Solana, the EU's foreign policy chief, will be in no mood to mince his words. His message to the Capabilities Improvement Conference - a meeting to assess progress on the rapid reaction force - will be that member states are moving too slowly towards increasing defence expenditure, crucial for the creation of the 60,000-strong force.

Agreed at the Helsinki Summit in December 1999, the rapid reaction force is supposed to be ready by mid-2003. It is intended to be capable of going into action within 60 days of any emergency and able to remain deployed for up to a year as far afield as Africa.

Under the terms of the Petersberg Tasks, named after a meeting of EU officials at a hotel near Bonn in 1992, the force will conduct operations from rescue missions to crisis management - independently of Nato, if Nato chooses not to lead it.

So far 100,000 troops, 400 aircraft and 100 ships have been pledged by member states. But, critics caution, this isalimited achievement. "We still have not seen any progress on precision-guided missiles, anti-air defence or forces' protection," says Klaus Buhler, a member of the German Bundestag and president of the Western European Union assembly, soon to become the European Security and Defence Assembly. All of these requirements, he adds, are essential.

Just how far Europe still has to go to launch the rapid reaction force is underlined in a new study by defence institutes in six EU countries. It says that sustaining the force will require 180,000 troops, given that units will have to be rotated. The total is equivalent to about a fifth of the non-conscript European soldiers not already assigned to foreign duties.

More telling, adds the report commissioned by the British government, many of the requirements for the force will not be met before 2008 or 2010. In the meantime, member countries will have to restructure their defence budgets radically to meet the extra expenditure - estimated at $25bn (£17bn) over the next 10-15 years, based on acquisition and initial running costs. "The bill would be much higher when the cost of supporting the extra systems was taken into account," the authors warn.

Europe's defence officials recognise the scale of the task ahead. But they insist that today's conference has gained urgency since the September 11 attacks.

For its war against the Taliban the US called not on Nato but individual European allies - Britain, France and Germany - for help. Washington did so mainly to keep complete hold over command and control structures. But it also saw that Europe lacked essential capabilities, such as intelligence, logistics, communications and air transport systems.

"These are exactly the problems we had during the Kosovo war," says Mr Solana, who was then secretary-general of Nato. "September 11 shows why the Europeans must be ready to contribute to peacekeeping and crisis management.

"We must go as quickly as possible in improving our capabilities - and that means intelligence-sharing."

Mr Buhler also believes that the Petersberg Tasks, influenced by Europe's poor showing in the Balkans during the 1990s, should be adapted to the changed security environment.

But some EU diplomats worry that changing tack now could lead to disarray and delays. Others say it is time to define exactly what constitutes a Petersberg-type operation.

Belgium, which holds the EU's rotating presidency, wants to declare the rapid reaction force "operational" by the end of this year at the Laeken summit of EU leaders. In practical terms, few officials can explain what this means, beyond saying the EU will have structures in place to assess conflicts.

As Mr Buhler says: "There is no sign of the increase in defence budgets that is necessary for all this. I do not see on what basis the EU is going to declare ESDP operational at Laeken."

Indeed, efforts to accelerate work on the rapid reaction force highlight the extent to which member states differ over the aims of an EU defence policy.

British officials argue that the force is more important than ever. They see it complementing Nato by providing further capacity for managing small-scale crises in regions such as Africa. For Britain, the force will strengthen the European arm of Nato. France, however, does not want the force to be so closely integrated into Nato, while Germany and Sweden want it to concentrate on peacekeeping. "We have to settle once and for all what ESDP is about," says a Dutch diplomat.

There are sharp disagreements too over how the rapid reaction force should be financed - over what counts as shared costs and how much should be paid by individual countries. "Without resolving that, there is little hope of addressing investment shortfalls," says a German diplomat.

Those issues are not likely to be resolved in Brussels today. But some progress is expected. Mr Solana, backed by most member states, will draw up a plan to improve Europe's military capabilities, with greater emphasis on co-operation between countries or groups of countries. The aim is to establish some form of "role specialisation" such as the recent agreement between the Netherlands and Germany to pay for strategic airlift. It will also recommend EU joint initiatives in areas including air transport and air-to-air refuelling systems.

These recommendations are fine on paper, argue military officials. But clearly agreed goals - the basis for securing more money - are still needed. "It is really a question of political will," says General Mertil Melin, Sweden's military representative on the EU's committee that oversees security and defence policy. "We have to start explaining to our own publics why Europe has to be able to provide security outside the region."